[trucheli]

I do my own oil changes on my 335i ZSP. I started using BMW 0W30 but I changed to Castrol 10W60 for added protection since I track my car. Now I want to change to Mobil 1 15W50 which is the closest grade available. Any opinions how the two compare would be appreciate it.

[epiphone3]

I think you are running oil that is too thick.... but if you must, I would go with the Castrol 10W-60 TWS motorsport. At least it is recommended by BMW.

Honestly though, I personally think that you should oil in the range of weights that your car is designed for. Thicker oil does not always equal better protection as often times, the oil system cannot sustain the same film of oil between critical parts with the thicker oil due to higher pressure drops.

Keep in mind Formula 1 engines typically use 10W20 or 0W20 oil to race at 19,000rpm and higher levels of heat than your 335i.

[RMRC]

I agree with epiphone3. The manual recommends either 5W30 or 5W40 (for warmer climates). I'd imagine using other viscosity oils could result in a voided warranty should something inside go bad.

[trucheli]

If 10W60 is good enough for the M3 (non turbocharged) I think it only would help the E92. Mobil 1 15W50 is recommended for Turbocharged engines.
Thanks for your reply.

From Bimmer Magazine

http://bimmer-mag.com/art1/art1p4.html

[noro]

15-50 is too thick for that engine 5-40/10-40 is what you want to use

also if you track your car Red Line 10w40 is probably one of the best oils you can use, but it's expensive

[AR230WAKEBOARDER]

I Have been using Redline 5-30 and am happy with it. I have Not burned any oil on the 7000 mile durations I have run it.

[trucheli]

Originally Posted by noro

15-50 is too thick for that engine 5-40/10-40 is what you want to use

also if you track your car Red Line 10w40 is probably one of the best oils you can use, but it's expensive

I like RedLine also. I have been paying $9 per quart for Castrol 10W60. I can get RedLine for the same price.

Remember, the issue with the E92 is HEAT, that's why the change of grade.

[epiphone3]

Originally Posted by trucheli

If 10W60 is good enough for the M3 (non turbocharged) I think it only would help the E92. Mobil 1 15W50 is recommended for Turbocharged engines.
Thanks for your reply.

From Bimmer Magazine

http://bimmer-mag.com/art1/art1p4.html

Its really not a question of "its good enough for the M3." It is a question of the design of the oil system and the tolerances in the engine. Thicker oil resists flow more... this means higher pressure drops... higher pressure drops means the oil system may not be able to maintain the protective film of oil between vital engine parts like the crank and main bearing journals etc. with such a thick oil.

Seriously, thicker oil does not necessarily offer more protection and in this case likely offers less protection. The oil system is designed to pump the thinner oil at the pressures required for the engine.

If you really must go with a thicker oil, run 5W40 or 0W40 instead of 5W30 or 0W30.

If you are worried about HEAT, get supersprint down pipes to carry the hot exhaust away from the engine more quickly.

[Revlis]

Heavier oil might be an issue... I'd stick with an OEM weight but maybe go with a premium Full synthetic.

Besides heavier oil robs power and in an engine designed for a very specific weight going with a much heavier weight is probably a really bad idea.

[epiphone3]

Originally Posted by Revlis

Heavier oil might be an issue... I'd stick with an OEM weight but maybe go with a premium Full synthetic.

Besides heavier oil robs power and in an engine designed for a very specific weight going with a much heavier weight is probably a really bad idea.

+1

If you track the car, maybe run a proper weight oil that is focused for racing like Redline or Motul or something. Then dump the oil once you've left the track or something.

People have this ficticious notion that thicker oil protects better... this is not the case unless the engine is designed for it.

[Neema]

Too thick, and Motul 300v is the best oil, but VERY EXPENSIVE. its about $20-30 per 2 liters.... It costs me about $120 to use it for my e92 (which takes about 6.5 quarts). And yea, use 5w-30/40, or 0w- 30/40. Thicker oils cant get into the tight seals and seams of an engine that doesnt recomend that, atleast thats what i was told be a bmw tech when i asked about 10w-50's and up.

[rbaldwin28]

The only time you should ever use 10w60 is on a track only when you see much higher sustained temps. 99% of engine wear happens at start up when your oil is at ambient air temp and does not flow well. Remember flow= lubrication. Mobil 1 0w40 will get to its proper flow rating faster than the 10w60 and will protect much better for start up and drive conditions like most people see. Change your oil if you go to the track and you are worried about heat and viscosity at 300 degrees.

[742]

IMO, given your concerns, you should look more at HTHS and less at the advertised viscosity numbers.

Use the available LL01 oil with the highest HTHS.

[Boogster]

I am switching to full synthetic 0W30 for my 335i Dinan Stage 2. Their are two reasons. First, all oils have very similar viscosities at around 210 degrees, the warm engine temp. that means their 'fresh oil" ability to protect your engine are the same or very close to the same. The additives oil producers place in the oils allow them to be used longer, controlling the "dirt" that builds up in them and to make the dirt large enough for your oil filter to remove, and lots more. What is more critical is the oil state at engine startup. All oils are significantly thicker at normal air temp. this thickness prevents them from being pumped as efficiently into and around all the engine parts. This is why you are not supposed to do WOT's and drive "spirited" in any car when its engine is cold. NO OIL CAN LUBRICATE AN ENGINE EFFICIENTLY WHEN IT IS COLD AND THAT IS BECAUSE IT IS TOO THICK. So the concern with street drivers is how does that oil act at start up and then, how long does it last (economy).

Oil technology has improved a lot over 20 years. The full synthetics can last a long time. More importantly, oils like to 0W20 or 0W30 or 0W40 all are a lot thinner at start up compared to 5W30 or 5W40. They are able to more easily keep the bearings bathed in oil and hence, keep them lubricated without breaking down. BMW is not in the oil business. They engineer cars. They trust the folks who make the oils they sell, but they also, like any company, shop on price as well, just like we do. They have good oils, but there are better solutions to lubrication than what BMW sells.

If you want to stay with theirs, good for you. If you want to use something better, that is great as well. It's your car, do what you want with it. Me, I'll use full synthetic 0W30, probably just Mobil 1 or maybe Amsoil. I am not racing. I like to drive spirited and do an occasional WOT. 385 horsepower is a terrible thing to waste! I plan have my oil tested every 4000 miles for breakdown. I do not expect any problems.

Now if anyone has good technical knowledge regarding various oil filters and which is best for my Beemer, I'd love to learn more on this still.

This is a very good site where you can learn a ton about engine oil.
http://www.bobistheoilguy.com/motor-oil-101/

[Surly73]

trucheli:

The first question to answer to determine if you need to go outside spec for your track oil is to tell us your track oil temps. You really only need to go up in visc if you're getting really high temps. If your oil temperature is under control, don't assume that uber-thick is automatically and always better in some way (as others have already pointed out).