Discussion
When I bought my motor, I was advised thta because of the nature of the RV8 and it's 'age' it runs best on normal oil eg. Castrol GTX, and the guy kindly handed me a full can of the stuff. Now having read the Bible I see that He recommends synths. I'm not ready for an oil change and the motor hasn't used any since I got it a month ago but I'm concerned as to what I should be using.
A friend told me that he uses semi-synth because once the engine's used some mineral you can't switch totally to synth, but having looked at the Mobil 1 page I see that this may be a myth.
So, I've got a motor (only 2500miles) running with mineral; what to do next change?
Tnx in anticipation from all you experts :noironysmilie:
A friend told me that he uses semi-synth because once the engine's used some mineral you can't switch totally to synth, but having looked at the Mobil 1 page I see that this may be a myth.
So, I've got a motor (only 2500miles) running with mineral; what to do next change?
Tnx in anticipation from all you experts :noironysmilie:
I was advised by main and specialist dealers to use Valvaline (not sure of spelling) in mine which is a semi synthetic oil and I've had not problems, car hardly uses any, TVR and dealers used to recommend Mobil One, but I have been told that this was only because Modil sponsored the Tuscan Challenge, again from different sources.
I don't under stand the mineral oil/sync senerio, when I had my new Chimera the run in order was cheap crap mineral for 500 miles, then replaced with Semi for 500 miles then Mobil one, that was in the mobil one days.
Hope this helps.
I don't under stand the mineral oil/sync senerio, when I had my new Chimera the run in order was cheap crap mineral for 500 miles, then replaced with Semi for 500 miles then Mobil one, that was in the mobil one days.
Hope this helps.
I suggest you keep with the viscosity level recommended in the manual (20W50??) and then look for the best quality as defined by API. You will find this listed on the back of the can and the quality level increases from SA, SB, SC etc through to the current SL (no SI or SK). I wouldn't use anything less than SG. You may have difficulty in finding SL as a 20W50 but there will be plenty of SJ or SH to choose from. Unless you really give it some stick all the time (track use??) the synthetics or semi-synthetics are (IMHO) a waste of money.
Years ago I also phoned some dealerships to be told that Mobil 1 had and would always be recommended for all TVRs. Funny as the plate on the inner wing recommends "Century Supreme Synthetic Motor Oil"
At the time a friend of mine had recently worn a set of cams out on his Chevette HS (DOHC Vauxhall 2.3l slant 4), and attributed it to recently changing to 0W oil, I questioned the wisdom in changing viscosity so drastically.
Although oil chemistry has advanced over the 25plus years since the V8 engine was designed, I have a certain respect for the designers and take on board their recommendations. My engine is original, an un-breathed on 3.5 injection unit, as used in the SD1 Vitesse and as such I don't see why it would require different oil to the Vitesse (perhaps driving style)
After a lot of deliberation I decided on Mobil 1 motorsport from Halfords.
This is fully synthetic and similar viscosity to the original manufacturers spec.
So I maintain my respect for the designers/manufacturers and make use of the newer technical developments in oils. I change oil once a year where I would have done this twice with lower quality oil. My time and the cost of extra filters offset the higher cost of oil.
Hope this helps in your decision. If you go the cheaper oil, more frequent change route then I recommend Castrol GTX.
Leo
At the time a friend of mine had recently worn a set of cams out on his Chevette HS (DOHC Vauxhall 2.3l slant 4), and attributed it to recently changing to 0W oil, I questioned the wisdom in changing viscosity so drastically.
Although oil chemistry has advanced over the 25plus years since the V8 engine was designed, I have a certain respect for the designers and take on board their recommendations. My engine is original, an un-breathed on 3.5 injection unit, as used in the SD1 Vitesse and as such I don't see why it would require different oil to the Vitesse (perhaps driving style)
After a lot of deliberation I decided on Mobil 1 motorsport from Halfords.
This is fully synthetic and similar viscosity to the original manufacturers spec.
So I maintain my respect for the designers/manufacturers and make use of the newer technical developments in oils. I change oil once a year where I would have done this twice with lower quality oil. My time and the cost of extra filters offset the higher cost of oil.
Hope this helps in your decision. If you go the cheaper oil, more frequent change route then I recommend Castrol GTX.
Leo
Gerry Attrick said:
I suggest you keep with the viscosity level recommended in the manual (20W50??) and then look for the best quality as defined by API. You will find this listed on the back of the can and the quality level increases from SA, SB, SC etc through to the current SL (no SI or SK). I wouldn't use anything less than SG. You may have difficulty in finding SL as a 20W50 but there will be plenty of SJ or SH to choose from. Unless you really give it some stick all the time (track use??) the synthetics or semi-synthetics are (IMHO) a waste of money.
Don.
Thats interesting, so where doe's the Valveline semi fit in to the equation, as I believe this is what most of them recommend.
Martin
Suggest you talk to an expert,there just happens to be one on General Gassing
www.pistonheads.co.uk/gassing/topic.asp?t=124184&f=13&h=0
If you get a response perhaps you would post it up for us all
www.pistonheads.co.uk/gassing/topic.asp?t=124184&f=13&h=0
If you get a response perhaps you would post it up for us all
stever said:
Suggest you talk to an expert,there just happens to be one on General Gassing
www.pistonheads.co.uk/gassing/topic.asp?t=124184&f=13&h=0
If you get a response perhaps you would post it up for us all
Seems to know his stuff, how you doing been out playing recently Steve.
It seems to be generally accepted that the RV8 oil system prefers thicker oils. To quote David Hardcastle from his excellent book Tuning Rover V8 Engines: The RV8 does not like modern lightweight oils such as 5W-50 because it cannot be pumped in volume in the same way as heavier oils, although oil pressure is maintained. The system is a high volume system, not high pressure....... For competition use the engine needs SAE 30 or 40.
Having said all that, the '94 engine in my 4.3se has been run on Mobil 1 since its first oilchange, although I have used the French spec. 5W-50 for the past 6 years without any problems which could be attributed to the oil. For a road car which is used all year round, I think that a 5W rated oil gives better protection than a heavier one on cold start-up, which is when the majority of wear takes place. The MSport 15W rated stuff is fine if you only use the car in the summer.
Having said all that, the '94 engine in my 4.3se has been run on Mobil 1 since its first oilchange, although I have used the French spec. 5W-50 for the past 6 years without any problems which could be attributed to the oil. For a road car which is used all year round, I think that a 5W rated oil gives better protection than a heavier one on cold start-up, which is when the majority of wear takes place. The MSport 15W rated stuff is fine if you only use the car in the summer.
redcar said:
Seems to know his stuff, how you doing been out playing recently Steve.
Hi Martin, doin good thanks trust the same with you.
Not playing much lately, last time was a trip with Seamus and DP400 to Goodwood Revival, an excellent day out, recommended for a big Wedge gathering next year.
A few locals are meeting this Sunday (7am
) if you can't sleep and want to come to Bucks drop me an email. Catch up soon for a Southern Wedge Meet???
Gents, found this on another web site. Thought it made interesting reading. Not sure how much of it applies to the RV8 engine. Don't know the company or have any connection with it but worth e read.
If you are running a car above the stock BHP with higher engine temperatures or in competition then use "true" synthetic oils for the best protection.
SAE has a test called HT/HS (High Temperature/High Shear) ASTM D4683 at 150 degC.
The higher the HT/HS number the better because this indicates less shearing. Petroleum oils tend to have low HT/HS numbers which barely meet the standards set by SAE. Because petroleum oils are made with light weight basestocks to begin with, they tend to burn off easily in high temperature conditions which causes deposit formation and oil consumption.
As a result of excessive oil burning and susceptibility to shearing (as well as other factors) petroleum oils must be changed more frequently than synthetics.
Not all multi-viscosity oils shear back so easily. True synthetic oils (PAO’s and Esters) contain basically no waxy contamination to cause crystallization and oil thickening at cold temperatures. In addition, synthetic basestocks do not thin out very much as temperatures increase. So, pour point depressants are unnecessary and higher viscosity basestock fluids can be used which will still meet the "W" requirements for pumpability.
Hence, little or no VI improver additive would need to be used to meet the sae 30, 40 or 50 classification while still meeting 0W or 5W requirements.
The end result is that very little shearing occurs within true synthetic oils because they are not "propped up" with viscosity index improvers. There simply is no place to shear back to. In fact, this is easy to prove by just comparing synthetic and petroleum oils of the same grade.
Synthetics will generally have significantly higher HT/HS numbers. Of course, the obvious result is that your oil remains "in grade" for a much longer period of time for better engine protection and longer oil life.
What is VI Improver?
As a lubricant basestock is subjected to increasing temperatures it tends to lose its viscosity. In other words, it thins out. This leads to decreased engine protection and a higher likelihood of metal to metal contact. Therefore, if this viscosity loss can be minimized, the probability of unnecessary engine wear will be reduced.
VI improvers are polymers that expand and contract with changes in temperature. At low temperatures they are very compact and affect the viscosity of a lubricant very little. But, at high temperatures these polymers "expand" into much larger long-chain polymers which significantly increase the viscosity of their host lubricant.
So, as the basestock loses viscosity with increases in temperature, VI improvers “fight back”
against the viscosity drop by increasing their size. The higher the molecular weight of the polymers used, the better the power of "thickening" within the lubricant. Unfortunately, an increase in molecular weight also leads to an inherent instability of the polymers themselves. They become much more prone to shearing within an engine.
As these polymers are sheared back to lower molecular weight molecules, their effectiveness as a VI improver decreases. Unfortunately, because petroleum basestocks are so prone to viscosity loss at high temperatures, high molecular weight polymers must be used. Since these polymers are more prone to shearing than lower molecular weight polymers, petroleum oils tend to shear back very quickly. In other words, they lose
their ability to maintain their viscosity at high temperatures.
Synthetic basestocks, on the other hand, are much less prone to viscosity loss at high temperatures. Therefore, lower molecular weight polymers may be used as VI improvers.
These polymers are less prone to shearing, so they are effective for a much longer period of time than the VI improvers used in petroleum oils. In other words, synthetic oils do not quickly lose their ability to maintain viscosity at high temperatures as petroleum oils do.
In fact, some synthetic basestocks are so stable at high temperatures they need NO VI improvers at all. Obviously, these basestocks will maintain their high temperature viscosities for a very long time since there are no VI improvers to break down.
Email us for a price list: sales@opieoils.co.uk
Cheers
Guy
__________________
sales@opieoils.co.uk
www.opieoils.co.uk/lubricants.htm
If you are running a car above the stock BHP with higher engine temperatures or in competition then use "true" synthetic oils for the best protection.
SAE has a test called HT/HS (High Temperature/High Shear) ASTM D4683 at 150 degC.
The higher the HT/HS number the better because this indicates less shearing. Petroleum oils tend to have low HT/HS numbers which barely meet the standards set by SAE. Because petroleum oils are made with light weight basestocks to begin with, they tend to burn off easily in high temperature conditions which causes deposit formation and oil consumption.
As a result of excessive oil burning and susceptibility to shearing (as well as other factors) petroleum oils must be changed more frequently than synthetics.
Not all multi-viscosity oils shear back so easily. True synthetic oils (PAO’s and Esters) contain basically no waxy contamination to cause crystallization and oil thickening at cold temperatures. In addition, synthetic basestocks do not thin out very much as temperatures increase. So, pour point depressants are unnecessary and higher viscosity basestock fluids can be used which will still meet the "W" requirements for pumpability.
Hence, little or no VI improver additive would need to be used to meet the sae 30, 40 or 50 classification while still meeting 0W or 5W requirements.
The end result is that very little shearing occurs within true synthetic oils because they are not "propped up" with viscosity index improvers. There simply is no place to shear back to. In fact, this is easy to prove by just comparing synthetic and petroleum oils of the same grade.
Synthetics will generally have significantly higher HT/HS numbers. Of course, the obvious result is that your oil remains "in grade" for a much longer period of time for better engine protection and longer oil life.
What is VI Improver?
As a lubricant basestock is subjected to increasing temperatures it tends to lose its viscosity. In other words, it thins out. This leads to decreased engine protection and a higher likelihood of metal to metal contact. Therefore, if this viscosity loss can be minimized, the probability of unnecessary engine wear will be reduced.
VI improvers are polymers that expand and contract with changes in temperature. At low temperatures they are very compact and affect the viscosity of a lubricant very little. But, at high temperatures these polymers "expand" into much larger long-chain polymers which significantly increase the viscosity of their host lubricant.
So, as the basestock loses viscosity with increases in temperature, VI improvers “fight back”
against the viscosity drop by increasing their size. The higher the molecular weight of the polymers used, the better the power of "thickening" within the lubricant. Unfortunately, an increase in molecular weight also leads to an inherent instability of the polymers themselves. They become much more prone to shearing within an engine.
As these polymers are sheared back to lower molecular weight molecules, their effectiveness as a VI improver decreases. Unfortunately, because petroleum basestocks are so prone to viscosity loss at high temperatures, high molecular weight polymers must be used. Since these polymers are more prone to shearing than lower molecular weight polymers, petroleum oils tend to shear back very quickly. In other words, they lose
their ability to maintain their viscosity at high temperatures.
Synthetic basestocks, on the other hand, are much less prone to viscosity loss at high temperatures. Therefore, lower molecular weight polymers may be used as VI improvers.
These polymers are less prone to shearing, so they are effective for a much longer period of time than the VI improvers used in petroleum oils. In other words, synthetic oils do not quickly lose their ability to maintain viscosity at high temperatures as petroleum oils do.
In fact, some synthetic basestocks are so stable at high temperatures they need NO VI improvers at all. Obviously, these basestocks will maintain their high temperature viscosities for a very long time since there are no VI improvers to break down.
Email us for a price list: sales@opieoils.co.uk
Cheers
Guy
__________________
sales@opieoils.co.uk
www.opieoils.co.uk/lubricants.htm
sevans said:
Gents,.....
Cheers
Guy
This is the guy that is writing all of the oil stuff on the General TVR and Engines forums. Basically he says that for RV8s use a fully syn 10/40 or 15/50 for many reasons don't go above 50 because that means too many additives and don't go below 10 because there's no benefit anyway: 5W for -30 and a 0W for -35 degrees C!
>> Edited by 19560 on Thursday 16th September 22:37
19560 said:
Gents,.....
Cheers
Guy
This is the guy that is writing all of the oil stuff on the General TVR and Engines forums. Basically he says that for RV8s use a fully syn 10/40 or 15/50 for many reasons don't go above 50 because that means too many additives and don't go below 10 because there's no benefit anyway: 5W for -30 and a 0W for -35 degrees C!
>> Edited by 19560 on Thursday 16th September 22:37
He's doing some plugging then. This was off the RS owners club website
opieoils are basically correct in what they say. However you have to ask yourselves whether the benefits offered by syntheitic or semisynthetic basestocks are of any real benefit in your engine.
Modern oils can be considered to be made up of three components; the basestocks, the viscosity improvers (VI) and additives.
Conventional paraffinic basestocks are a mixture of many hundreds of different lengths of long chain hydrocarbons, some of which are more stable than others. The less stable ones are likely to shear and thus reduce the oil's viscosity as the engine is used. The synthetic basestocks are made of a limited range of chain lengths and so they can be designed to be more resistant to shearing. This becomes important if you intend to use your cars for sustained high speed or high temperature operations. However, for more normal use, there is no advantage.
The original engines were designed to run on 20w50 oils, which means that at 40 degC the oil shoud act like a 20 grade and at 100 degC it should act like a 50 grade. To do this, VIs are added, which act in the way stated by opieoils. They can also be sheared so the oil becomes less viscous with time. However, modern VIs are far more stable than they were 20 years ago when the engine was first used in the Wedge. Also most of us change our oil more frequently than required so the amount of shearing is limited anyway.
If you use some of the more modern(eg 5W30) oils the overall viscosity will be lower, which will reduce the film thicknesses in the engine, and result in more metal to metal contact and increased wear.
Finally the additives. These are the real components that matter in the oil, as these are the ones that give anti-wear capability, sludge inhibition, deposit control, anti-rusting, fuel economy and long drain capability. The original Wedge engines were designed to run on API SF (some of the later ones on SG perhaps), and this defined a quality level attainabel at the time. Since then oil technology has progressed as much as in the previous 80 years. The use of synthetic basestocks may make the job of the oil formulator easier as he may need less VI or less anti-oxidant in the finished oil, but the final arbiter of oil quality is still the same. Two oils with the same API quality will still give the same anti-wear performance or deposit control. At the moment the API have just moved to SM quality from SL. The can of GTX I have in the garage is SL quality and so is essentially as good as it gets. As I don't use my car for racing and I don't drive from Helsinki to Naples in one high speed thrash, I don't think the synthetics will do a lot for me.
The API (American Petroleum Institute) website will give you more details of quality levels if you want it. There is a European organisation which also specifies oil quality for European car manufacturers (hence you will also see quality levels such as ACEA A2 or A3 on cans), but they are less well known worldwide than the API. They also work in the same way.
Don't get me wrong, I am not advocating the use of cheap inferior oils in your cars. I am merely suggesting that if you buy a quality level higher than you need you may be wasting money.
>> Edited by Gerry Attrick on Friday 17th September 15:17
Modern oils can be considered to be made up of three components; the basestocks, the viscosity improvers (VI) and additives.
Conventional paraffinic basestocks are a mixture of many hundreds of different lengths of long chain hydrocarbons, some of which are more stable than others. The less stable ones are likely to shear and thus reduce the oil's viscosity as the engine is used. The synthetic basestocks are made of a limited range of chain lengths and so they can be designed to be more resistant to shearing. This becomes important if you intend to use your cars for sustained high speed or high temperature operations. However, for more normal use, there is no advantage.
The original engines were designed to run on 20w50 oils, which means that at 40 degC the oil shoud act like a 20 grade and at 100 degC it should act like a 50 grade. To do this, VIs are added, which act in the way stated by opieoils. They can also be sheared so the oil becomes less viscous with time. However, modern VIs are far more stable than they were 20 years ago when the engine was first used in the Wedge. Also most of us change our oil more frequently than required so the amount of shearing is limited anyway.
If you use some of the more modern(eg 5W30) oils the overall viscosity will be lower, which will reduce the film thicknesses in the engine, and result in more metal to metal contact and increased wear.
Finally the additives. These are the real components that matter in the oil, as these are the ones that give anti-wear capability, sludge inhibition, deposit control, anti-rusting, fuel economy and long drain capability. The original Wedge engines were designed to run on API SF (some of the later ones on SG perhaps), and this defined a quality level attainabel at the time. Since then oil technology has progressed as much as in the previous 80 years. The use of synthetic basestocks may make the job of the oil formulator easier as he may need less VI or less anti-oxidant in the finished oil, but the final arbiter of oil quality is still the same. Two oils with the same API quality will still give the same anti-wear performance or deposit control. At the moment the API have just moved to SM quality from SL. The can of GTX I have in the garage is SL quality and so is essentially as good as it gets. As I don't use my car for racing and I don't drive from Helsinki to Naples in one high speed thrash, I don't think the synthetics will do a lot for me.
The API (American Petroleum Institute) website will give you more details of quality levels if you want it. There is a European organisation which also specifies oil quality for European car manufacturers (hence you will also see quality levels such as ACEA A2 or A3 on cans), but they are less well known worldwide than the API. They also work in the same way.
Don't get me wrong, I am not advocating the use of cheap inferior oils in your cars. I am merely suggesting that if you buy a quality level higher than you need you may be wasting money.
>> Edited by Gerry Attrick on Friday 17th September 15:17
i would not use a 5W-30 in the UK. this is essentially a ford spec oil and is low HTHS. 10W-40 is more suitable.
sorry to hi-jack the thread, but has anyone used anything but an ATF in the rover 5-speed manual gearbox, or is it essential that you do only use the ATF?
cheers
edit: we'l stick with the ATF, looks like a MTF is too thick.
>> Edited by skinny on Thursday 23 September 13:00
sorry to hi-jack the thread, but has anyone used anything but an ATF in the rover 5-speed manual gearbox, or is it essential that you do only use the ATF?
cheers
edit: we'l stick with the ATF, looks like a MTF is too thick.
>> Edited by skinny on Thursday 23 September 13:00
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