Mezger engine oil change frequency
Discussion
One for the racers:
My 996 with a street engine has done 2.5-3 hours racing since the last oil change. My local indy is recommending 2000 miles is perfectly acceptable between changes, but that makes me nervous.
Recommendations for frequency of changes please? (Preferably with supporting evidence but this being PistonHeads I look forward to refereeing an unsubstantiated s
t fight.)
Car will see little action over the winter season - maybe a couple of gentle track outings but not as stressful as racing.
My 996 with a street engine has done 2.5-3 hours racing since the last oil change. My local indy is recommending 2000 miles is perfectly acceptable between changes, but that makes me nervous.
Recommendations for frequency of changes please? (Preferably with supporting evidence but this being PistonHeads I look forward to refereeing an unsubstantiated s
t fight.)Car will see little action over the winter season - maybe a couple of gentle track outings but not as stressful as racing.
Harris_I said:
One for the racers:
My 996 with a street engine has done 2.5-3 hours racing since the last oil change. My local indy is recommending 2000 miles is perfectly acceptable between changes, but that makes me nervous.
Recommendations for frequency of changes please? (Preferably with supporting evidence but this being PistonHeads I look forward to refereeing an unsubstantiated st fight.)
Car will see little action over the winter season - maybe a couple of gentle track outings but not as stressful as racing.
Have not tracked my 996 Turbo but when I auto-x'd my Datsun 510 my auto tech buddies told me to always show up at the track with fresh oil. I only auto-x'd a couple of times a year so I'd change the oil a day or two before the event.My 996 with a street engine has done 2.5-3 hours racing since the last oil change. My local indy is recommending 2000 miles is perfectly acceptable between changes, but that makes me nervous.
Recommendations for frequency of changes please? (Preferably with supporting evidence but this being PistonHeads I look forward to refereeing an unsubstantiated s
t fight.)Car will see little action over the winter season - maybe a couple of gentle track outings but not as stressful as racing.
For both of my Porsches and with purely street driving with mostly highway miles I change the oil every 5K miles.
If you engage in mostly short trips I'd recommend you change the oil more often. Short trips loads the oil with among other things water and this lowers the viscosity of the oil. Even at 5K miles I notice the engine's a bit more tickity tickity not only at cold start but once warmed up. Hot idle oil pressure doesn't seem to be affected though.
If you drive some between track events I'd err on the side of caution and change the oil before each event.
I changed mine after every race weekend in the Cups. Gearbox was every second weekend. I wasn't unusual with that pattern.
UOA on both suggested that this was an interval that worked. It could have been pushed each a little more at certain times but it became dependant upon variables doing so. Changing both on this 1/2 schedule meant I could be sure the oil was doing what it should.
I don't know how hard you were working the thing, but you do, so the above can probably help as a marker.
If you were closer to track day than racing in terms of engine use you can probably push the schedule out a little. If it was typical track day running In terms of car effort then you can push it out further still. A rule of thumb for a track day seems to be to take a typical track day as ~2500 miles equivalent when it comes to oil. Just subtract it from your regular oil change interval mileage countdown and do it that way.
On the gearbox side, Matt at Guard reckoned ~4 days was a good point when it came to gearbox fluids and track days last I heard. It seems most people don't think about their gearbox fluid very much.
UOA on both suggested that this was an interval that worked. It could have been pushed each a little more at certain times but it became dependant upon variables doing so. Changing both on this 1/2 schedule meant I could be sure the oil was doing what it should.
I don't know how hard you were working the thing, but you do, so the above can probably help as a marker.
If you were closer to track day than racing in terms of engine use you can probably push the schedule out a little. If it was typical track day running In terms of car effort then you can push it out further still. A rule of thumb for a track day seems to be to take a typical track day as ~2500 miles equivalent when it comes to oil. Just subtract it from your regular oil change interval mileage countdown and do it that way.
On the gearbox side, Matt at Guard reckoned ~4 days was a good point when it came to gearbox fluids and track days last I heard. It seems most people don't think about their gearbox fluid very much.
I am not an expert on oil, but a few things to consider i would imagine would be the quality of oil, oil filter & environment. Assuming you are using an original Porsche Filter, Mobil 1 oil and not running in extreme hot/ dusty or extreme cold condition, which in the UK you won't be, I would have thought you could comfortably go the distance your independent dealer recommends.
It's worth remembering these engine run 24 hour races without an oil change and on the street Porsche are recommending service intervals up to 30,000kms on some cars. I am not racing/ track much these days, but I have always stuck to oil changes every 10,000kms/ 6,000 miles on my GT3s & GT2s and they get used with a combination of road & track days and are driven, similarly to you, reasonably hard most of the time. Touch wood i've never had an engine issue with any of them.
It's worth remembering these engine run 24 hour races without an oil change and on the street Porsche are recommending service intervals up to 30,000kms on some cars. I am not racing/ track much these days, but I have always stuck to oil changes every 10,000kms/ 6,000 miles on my GT3s & GT2s and they get used with a combination of road & track days and are driven, similarly to you, reasonably hard most of the time. Touch wood i've never had an engine issue with any of them.
If I were running my own race car - as opposed to driving someone else's who would therefore dictate how the car was run - I'd Change the engine oil after every race weekend and gearbox every two. As per Firano. My track day cars after every other track day for engine and every 4 for gearbox. I use Motul sport ester in my engines and Millers in my gearboxes.
The engines in the 24hr races are brand new when they start and junk at the end, assuming they make it there. They also use oil at a rate of about 1 litre every 1 1/2 hours once they get 4 hours into the race. It is replaced using a high pressure feed system. So they are having the engine oil changed during the race. It is almost changed twice over when looking at replacement volume.
Track day driving is not, in my experience, close to racing use in terms of engine effort. So track day driving is unlikely to stress the engine and the oil in the same way. As a result it shouldn't need replacing in as short a time. This seems to be borne out by results from regular track day users who get UOA. These point to a less enhanced service interval when compared to cars that are racing, but one that is greater than a car that only sees road use.
While understanding other peoples analysis can save reinventing the wheel when establishing your own interval, there is no reason to guess with this if one is interested and/or concerned. UOA will tell you how your oil is holding up and whether you should be changing more frequently or extending intervals. Being able to monitor wear via metal content can be useful if you get regular UOA to compare against, but the UOA will specifically tell you how your oil spec is against when new, and as a result whether it was in too long or not.
Steve, Motul 300V is rather tasty. Ester base stock oils are fantastic. The high pressure shear properties are worth it alone.
Track day driving is not, in my experience, close to racing use in terms of engine effort. So track day driving is unlikely to stress the engine and the oil in the same way. As a result it shouldn't need replacing in as short a time. This seems to be borne out by results from regular track day users who get UOA. These point to a less enhanced service interval when compared to cars that are racing, but one that is greater than a car that only sees road use.
While understanding other peoples analysis can save reinventing the wheel when establishing your own interval, there is no reason to guess with this if one is interested and/or concerned. UOA will tell you how your oil is holding up and whether you should be changing more frequently or extending intervals. Being able to monitor wear via metal content can be useful if you get regular UOA to compare against, but the UOA will specifically tell you how your oil spec is against when new, and as a result whether it was in too long or not.
Steve, Motul 300V is rather tasty. Ester base stock oils are fantastic. The high pressure shear properties are worth it alone.
Edited by fioran0 on Saturday 14th November 12:19
fioran0 said:
While understanding other peoples analysis can save reinventing the wheel when establishing your own interval, there is no reason to guess with this if one is interested and/or concerned. UOA will tell you how your oil is holding up and whether you should be changing more frequently or extending intervals. Being able to monitor wear via metal content can be useful if you get regular UOA to compare against, but the UOA will specifically tell you how your oil spec is against when new, and as a result whether it was in too long or not.
This.As everyone's situation is different, if it's important to you, then do the job properly.
This will ensure
a) your engine has the best protection
b) you don't chuck our planet's valuable resources (and your money) down the drain.
fioran0 said:
Steve, Motul 300V is rather tasty. Ester base stock oils are fantastic. The high pressure shear properties are worth it alone.
I wish you and Steve had not mentioned that! 
My intention is to replace with Porsche approved Mobil 0W40 (as I think is the norm with Cup cars).Ah dammit. Having made a firm decision in my head to go with Mobil 1, I'm now surfing the net for Motul 300V. Their marketing strategy might be their own worst enemy. Too many sub-brands (Competition/Chrono/Power/Power Racing/Le Mans/Trophy) unless all this means is a way to differentiate viscosity. I'll drop opieoilman a line...
NAS90 said:
a combination of road & track days and are driven, similarly to you, reasonably hard most of the time
I would say the demands on this car are now much harder than an average track day - similar to when we both competed some years back. I now have a vague recollection our engines would get fresh oil every couple of hours, and that was in a harsh climate. Did you ever strip down the 997 engine and take a look?Harris_I said:
I wish you and Steve had not mentioned that! My intention is to replace with Porsche approved Mobil 0W40 (as I think is the norm with Cup cars).
I think most of the Porsche racers use 300V in Germany, my engine builder does in the race and highly tuned motors, apart from the shear thingy mentioned it is also very effective in maintaining its performance with fuel dilution which occurs with higher power engines. the 15/50 is my builders choice. My intention is to replace with Porsche approved Mobil 0W40 (as I think is the norm with Cup cars).Having said the above I have bought some Millers Nanodrive CFS NT 10/50 for my next oil change my thinking was the Millers is ester based and the 10 bit is probably more suitable for the engine for winter driving.
My 3.9l 800hp Mezger uses a litre every ~2000 miles and I change at about 4000.
For the OP's standard lump I would have thought these fancy ester oils are probably overkill and a low powered motor like this would not benefit from the shear properties like a very high power one will.
Harris_I said:
Dead easy if you are not an idiot like me. Today I spent 2 hours swapping out my race seat for the originals. Most of that was swearing.
Good advice on the lab sample. I am curious to know how the oil shapes up especially after the recent engine rebuild...
Oil sampling/analysis is a pain. The procedure that is recommended is to with the engine up to temperature remove the oil filter housing and pour some of this oil into a sample bottle. Then send the bottle off to be analyzed. Good advice on the lab sample. I am curious to know how the oil shapes up especially after the recent engine rebuild...
Then you get to wait. If the analysis comes back "OK" fit a new filter and new o-rings and install the housing. Then top up the oil again once the engine is warmed up. If the oil is deemed in need of replacement then you get to drain cold oil.
The procedure is bad enough I only analyzed the oil one time with my Boxster. The Turbo engine has the filter up top and upside down so one can't get away without making a mess.
Since I'm serious about my cars and my engines to me the oil is the sacrificial component of the oil/engine combination.
To that end I'd show up at every track event with fresh oil.
If you rely on analysis then you have to be prepared to decide how much oil degradation you can "live" with and how much oil degradation you hope your car's engine can live with. Is "10%" ok? What about "15%"?
Take the worry out of tracking, well, some of the worry, and just show up with fresh oil on track day. You can then enjoy the day knowing you have done what you can to protect the engine against the severe usage tracking subjects it to.
I haven't heard of that approach to UOA. Removing some and waiting to see what results come back while it remains in service sounds like a difficult way to do it.
I have always just kept some back when changing the oil out. Sent it off and waited for the analysis.
I would then use those results to inform the next interval going forwards. It becomes an iterative process.
If the oil I just threw away still looked good after analysis I can try extending service life a little longer and repeat. If it looked like it had been in a little too long I go back to the last known good position.
On the Cups, I always had good numbers returned from UOA after a race weekend. Numbers after leaving the oil in for a second weekend were variable. Sometimes they looked good, other times they didn't. It became dependant upon a bunch of variables. How many flags, how hot was it at the track, how hard was the race etc etc. As a result, replacing every weekend meant I could be sure the oil was always capable.
Harris, the Motul is all 300V. The weird names are just viscosity related, but are off putting I agree.
BTW, Mobil 1 is a good oil IMHO. Never had a problem with it and used it plenty in the Cups. An ester base stock makes for a better oil, but it doesn't make the Mobil 1 bad.
I have always just kept some back when changing the oil out. Sent it off and waited for the analysis.
I would then use those results to inform the next interval going forwards. It becomes an iterative process.
If the oil I just threw away still looked good after analysis I can try extending service life a little longer and repeat. If it looked like it had been in a little too long I go back to the last known good position.
On the Cups, I always had good numbers returned from UOA after a race weekend. Numbers after leaving the oil in for a second weekend were variable. Sometimes they looked good, other times they didn't. It became dependant upon a bunch of variables. How many flags, how hot was it at the track, how hard was the race etc etc. As a result, replacing every weekend meant I could be sure the oil was always capable.
Harris, the Motul is all 300V. The weird names are just viscosity related, but are off putting I agree.
BTW, Mobil 1 is a good oil IMHO. Never had a problem with it and used it plenty in the Cups. An ester base stock makes for a better oil, but it doesn't make the Mobil 1 bad.
Harris_I said:
NAS90 said:
a combination of road & track days and are driven, similarly to you, reasonably hard most of the time
I would say the demands on this car are now much harder than an average track day - similar to when we both competed some years back. I now have a vague recollection our engines would get fresh oil every couple of hours, and that was in a harsh climate. Did you ever strip down the 997 engine and take a look?Gassing Station | 911/Carrera GT | Top of Page | What's New | My Stuff