Switch from M1 15w50 to a 5w30

[Garak]

Originally Posted By: rooflessVW
How will I blow my engine if the original spec for all temperatures is 10w30. What makes the 5w30 so drastically different?


It's also important to remember, as CATERHAM pointed out, that many 5w-30s and the like available in Germany will be A3/B3 oils, and not the SN/GF-5 resource conserving oils we typically get in North America. I believe the M1 HM is A3/B3, but we don't get it in Canada anyhow.

 

[rrounds]

M1 5/30 or 0/40 is a good choice for your 280 but I would add 1 or 2 qt's of M1 0/50 racing oil to boost the Z/P of the oil(no more than a 50/50 mix for the street).
M1 0/50 racing oil has boosted levels of anti-wear protection -- well beyond those of ordinary automotive oils -- to help protect engines even during grueling racing applications. But it has way to much Z/P to run all by its self in a street car.

http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_Racing_0W-50.aspx

ROD
edit: I just looked and see your not in the US, I don't know if your oil has more Z/P than what we have in the US, but if your oil does have more Z/P. Then I would NOT use any M1 0/50 racing oil.

 

[supercity]

Did anyone suggest GC 0w30?

I'd use Helix Ultra 5w40 or Castrol Edge 5w30 A3/SL.

 

[Gokhan]

Originally Posted By: rooflessVW
But which one? I have been using M1's 15w50 because my 280zxt has an oil cooled turbo, and my Schneider camshaft is known to possibly have wear issues with some low ZDDP modern oils. To my knowledge, M1 15w50 is a high ZDDP oil, and I have had no issues with abnormal wear thus far.

My engine has about 5,000 miles on it since the rebuild, and I'd like to switch to a 5w30 for better fuel consumption and honestly, lower oil pressure. My oil pressure gauge seems constantly pegged once I am off-idle. Original spec for the engine is 10w30, 10w40, or 20w50, but that was in 1982 and I know oils have come a long way.

So, I'm going 5w30. My choices are between PU and M1, and I know they're both fine oils. I'm leaning more towards the PU, but I've read that switching between brands can cause some wear. Something about the oil film being removed when you switch brands.

What do you guys think? Stick with M1, or switch to PU? I plan on using 5w30 year round from now on, and for the life of the vehicle.

Someone just pointed out this study to me. Look at them and pick up one of the cleanest. M1 0W-40 or BMW LL 0W-40 etc. should be fail-safe but some quality synthetic 5W-30 could also work. Thinner oils will protect less in such heavily demanding turbo, high-power applications but then you get better fuel economy with them. However, there is no need to go as thick as xW-50 -- they are mainly for demanding diesel or motorcycle applications.

http://bmwservice.livejournal.com/27699.html
(Translate using the Google Chrome browser)

 

[RooflessVW]

Oil pressure with the oil @ 190f is just over 4bar, closer to 4.5bar @ 3000rpms. I think my engine will be fine. I think it's highly unlikely I'll have any sort of oil-related failure. It certainly isn't going to "blow up."

Starts and runs so much better in the cold, and revs more freely! I think I made the right choice. It should be good year round, my oil cooler keeps temps pretty steady, even when it's 90+f outside.

 

[RooflessVW]

And I called up Schneider Cams, they suggesting adding two shot glasses of the break-in additive they supplied. They also said they have been using higher quality billets than before, and I should be ok.

 

[Gokhan]

Originally Posted By: rooflessVW
Oil pressure with the oil @ 190f is just over 4bar, closer to 4.5bar @ 3000rpms. I think my engine will be fine. I think it's highly unlikely I'll have any sort of oil-related failure. It certainly isn't going to "blow up."

Starts and runs so much better in the cold, and revs more freely! I think I made the right choice. It should be good year round, my oil cooler keeps temps pretty steady, even when it's 90+f outside.

Lower the oil pressure, better it is for the engine, as long as it's not due to mechanical failure. That way you get better oil flow without your oil pump doing too much work and the bypass valve doesn't open and let dirty oil. Therefore, in that respect, the thinner the kinematic viscosity, the better it is.

Back in the 1980s, they didn't recommended 5W-30 because they didn't have synthetic 5W-30 and dino 5W-30 sheared like crazy, shearing from 30 to 10 weight. Fully Synthetic 0W-30 and 5W-30 don't shear and they are equivalent to 10W-30 for all practical purposes. Modern dino 5W-30 shears to xW-20 weight; so, it's better than in the 80s but still pretty bad. So, if you're running 10W-30 dino, fully synthetic 0W-30 and 5W-30 will offer the same or better protection but if you run 5W-30 dino, you may risk running an oil a little too thin (like 20 weight) because of shearing effects. On top of that, 5W-30 dino will result in a lot of sludge in certain engines due to the excessive usage of viscosity-index-improver polymers. Quality fully synthetic 0W-30 or 5W-30 don't have this problem, and they stay about as thick as the 10W-30 weight (HTHS viscosity ~ 3.0 cP) after they shear.

 

[Cujet]

Stick with the 15W-50 if you have mods, or are seriously worried about the camshaft. The oil's viscosity also helps protect the lobes. ZDDP is not the only issue with regard to cam life.

Aircraft engines, for example, use straight 50 viscosity oils, without ZDDP. Thinner oils do exhibit higher wear rates in many aircraft engines. Especially turbocharged ones.

Another excellent option is M1 5W-40 Turbo Diesel Truck. It's a very robust oil, with an excellent additive package.

 

[RooflessVW]

I firmly believe that an aircraft reciprocating engine and an automotive engine have so little in common with regard to life cycle and operating conditions that there was almost no point in making the comparison.

That being said, I may use the M1 5W-40 TD Truck oil this summer, if my oil pressure drops out of spec. If my oil pressure stays fine I'll probably continue to use the 5W-30.

Truth be told, I wouldn't be heartbroken if the Schneider gave up. I think I'm going back to an OEM N/A grind here in the near future.

 

[CATERHAM]

Originally Posted By: rooflessVW
Oil pressure with the oil @ 190f is just over 4bar, closer to 4.5bar @ 3000rpms. I think my engine will be fine. I think it's highly unlikely I'll have any sort of oil-related failure. It certainly isn't going to "blow up."

Starts and runs so much better in the cold, and revs more freely! I think I made the right choice. It should be good year round, my oil cooler keeps temps pretty steady, even when it's 90+f outside.

Your comfortably above the recommended minimum oil pressure test spec's for the engine so the oil is obviously not too light and should be more than fine over the summer.