Discussion
Hello,
If one changes ones oil at regular intervals, say 3-5k miles, is it really necessary to buy the most expensive synthetic oil, like Millers or Mobil 1?
I spoke to a guy (down the pub) and he reckons that if you buy the cheaper motor stores stuff, like the A1 motor stores chain has, it is rated to the same spec as the brands mentioned above and is made by well know oil manufacturers.
I know you shouldn't skimp on engine oil, but is it really necessary to fork out £35 on oil you will soon change?
Your comments are welcome.
Synthetic oil lasts longer, so if you spend £30 a gallon you don't have to change it every 3k miles, Mineral oils sludge quicker and degrade quicker (not necesarily related to miles)
Higher quality oils have better ingredients, if your car doesn't deserve fillet beef, feed it iceland burgers (or a half decent stewing steak like my Range Rover)
Edited to add that I'm really not an expert, but I have talked to people who decribe their job as "Petroleum Chemists" hardly understood a word they said
>> Edited by incorrigible on Wednesday 27th November 11:58
Higher quality oils have better ingredients, if your car doesn't deserve fillet beef, feed it iceland burgers (or a half decent stewing steak like my Range Rover)
Edited to add that I'm really not an expert, but I have talked to people who decribe their job as "Petroleum Chemists" hardly understood a word they said
>> Edited by incorrigible on Wednesday 27th November 11:58
Depends on the car etc etc etc....
Fully synthetic oils have a smaller molecule and are generally "thinner", which means that on some engines they just leak away ........ piston bores, valve stems oil seals, it'll just go.
If the engine manufacturer recommends a fully synthetic, then thats a different story.
For natural oils, however, it is the additive package that breaks down and has to be cleaned from the oil before the oil can be re-used. So generally, the more expensive the oil, the better the additive package. If you are doing the miles in a reasoable time frame and it is not all stop-start, short drives, then a cheap oil will be perfectly adequate IMHO. If its all stop-start then pay more for better additives....
Fully synthetic oils have a smaller molecule and are generally "thinner", which means that on some engines they just leak away ........ piston bores, valve stems oil seals, it'll just go.
If the engine manufacturer recommends a fully synthetic, then thats a different story.
For natural oils, however, it is the additive package that breaks down and has to be cleaned from the oil before the oil can be re-used. So generally, the more expensive the oil, the better the additive package. If you are doing the miles in a reasoable time frame and it is not all stop-start, short drives, then a cheap oil will be perfectly adequate IMHO. If its all stop-start then pay more for better additives....
Dont run non synth in ya gtir as it will degrade quickly coz of the heat & stress from the turbo.
PS if you think £35 is a lot on oil an air cooled 911 has around 12 litres of the oily stuff, so it costs well over £100 to change the oil on those with mob 1.
I personally always change oil at half the manufacturers recomended intervals on my own cars with a reasonable quality oil, I drive em hard but usually get to 150-200k without engine problems even on crappy old vauxhalls etc.
PS if you think £35 is a lot on oil an air cooled 911 has around 12 litres of the oily stuff, so it costs well over £100 to change the oil on those with mob 1.
I personally always change oil at half the manufacturers recomended intervals on my own cars with a reasonable quality oil, I drive em hard but usually get to 150-200k without engine problems even on crappy old vauxhalls etc.
This is my point, people say that the more expensive the better it is. Is it?
If cheaper oil has the same specification as the top brands than is it really inferior?
As for oil "leaking away" not sure if I understand what you mean, as ther is always a supply of oil so you never are in the situation where the parts are oil starved, in fact if its thinner it will lubricate better. Or am I being bim?
If cheaper oil has the same specification as the top brands than is it really inferior?
As for oil "leaking away" not sure if I understand what you mean, as ther is always a supply of oil so you never are in the situation where the parts are oil starved, in fact if its thinner it will lubricate better. Or am I being bim?
Synthetic oils are always recommended for turbo motors, not just because of the extra engine heat in them, but because lubrication of the turbo bearing is so important - it gets really hot, and mineral oils can coke up around it. Synths are less prone to this.
That's why it's so important to let a turbo car idle for a minute or two after a hard run before switching off - otherwise the oil pump stops, and oil just sits on the bearing which is severely hot (after running at 60-80k rpm at full boost) and carbonises. Running the engine means that a flow of cool oil is directed over the bearing until it's temperature drops back to normal.
That's why it's so important to let a turbo car idle for a minute or two after a hard run before switching off - otherwise the oil pump stops, and oil just sits on the bearing which is severely hot (after running at 60-80k rpm at full boost) and carbonises. Running the engine means that a flow of cool oil is directed over the bearing until it's temperature drops back to normal.
gtir said: This is my point, people say that the more expensive the better it is. Is it?
If cheaper oil has the same specification as the top brands than is it really inferior?
As for oil "leaking away" not sure if I understand what you mean, as ther is always a supply of oil so you never are in the situation where the parts are oil starved, in fact if its thinner it will lubricate better. Or am I being bim?
Very thin synths like 0w-40 (or is it 0w-30?) mobil 1 because it is so thin and coz of its man made constuction, tends to find its way out of the engine through gaskets and seals that may have been oil tight for many years with mineral or semi synthetic oils.
On non turbo cars I dont belive you need to spend huge amounts on oil, most big manufacturers semi synths are great - i think Castrol magnatec is the best in the market (IMHO) however for a turbo you really need a syntehic oil, you dont need the vastly over priced mob 1 - in fact i dont like the stuff as lots of cars ie AMG Mercs have high oil consumption on mob 1, but use a different oil and the consumptuon can reduce to nil!
Edited coz of truely awful spelling
ps added- think which is cheaper running crap oil or a new turbo
>> Edited by iguana on Wednesday 27th November 13:12
Fully synthetics have a higher tolerance to heat so that on cool down coking is a lot less of a problem.
Having said that, i still let my turbo cool for a couple of minutes even though i use castrol Rs 0/40, and even thought the turbo is watercooled.
I would avoid like the plague, any of that cheap oil, its recycled!
Re-engineered even, but will never be as good as a decent high grade mineral oil.
Having said that, i still let my turbo cool for a couple of minutes even though i use castrol Rs 0/40, and even thought the turbo is watercooled.
I would avoid like the plague, any of that cheap oil, its recycled!
Re-engineered even, but will never be as good as a decent high grade mineral oil.
Using fully synthetic oil really only justified in most modern and very high performance motors. Older designed engines (unless screaming turbos) can get by quite happily with semi-synthetic or equivalent. Most important is regular changes of oil and filter at or before recommended interval. Thrashing the engine once its warm is less of a problem for oil than never getting the engine warm enough to evaporate off water from combustion process. I think this may have been covered in some detail in a previous thread.
gtir said: Sorry, but that Castrol Magnetec is a load of marketing crap!
Well with what you seem to know about oil, or rather dont know, that is a bit strong dont you think!
Myself and many of my mates with many years in the motor industry & others with engineering degrees & masters in the petro chem industry tend to disagree with that statement.
Ho hum.
bikerkeith said: Using fully synthetic oil really only justified in most modern and very high performance motors. Older designed engines (unless screaming turbos) can get by quite happily with semi-synthetic or equivalent. Most important is regular changes of oil and filter at or before recommended interval. Thrashing the engine once its warm is less of a problem for oil than never getting the engine warm enough to evaporate off water from combustion process. I think this may have been covered in some detail in a previous thread.
Define "very high performance motors"?
After all you do drive "slow cars"!
iguana said:
gtir said: Sorry, but that Castrol Magnetec is a load of marketing crap!
Well with what you seem to know about oil, or rather dont know, that is a bit strong dont you think!
Myself and many of my mates with many years in the motor industry & others with engineering degrees & masters in the petro chem industry tend to disagree with that statement.
Ho hum.
Hey, who am I to disagree with someone with so much knowledge crammed into there brain!
It was supposed to be tounge in cheek, maybe we need a :toungeincheek: smiley?
Maybe you can tell me if it matters if oil really does stick the skirt of a piston?
Piston skirts "can" come into contact with the cylinder bore, so having an oil coating on them is a good thing - think of the way the piston moves within the bore at TDC and BDC and imagine the forces acting on it (full speed up to full speed down in nano-seconds at full chat...)and remember that it rotates about a gudgeon pin. The oil film is important.
deltaf - re-cycled oil is fine - the mineral oils dont breakdown at all IIRC and when stripped of the old additives and a new package added, is just as good as "virgin" oil......
deltaf - re-cycled oil is fine - the mineral oils dont breakdown at all IIRC and when stripped of the old additives and a new package added, is just as good as "virgin" oil......
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