Currently working on oil choice for two applications:
1. Completely stock. Calls for ISLAC GF-4 (API SM with starburst) 5w-20. Potential for high heat and high fuel dilution. Prone to carbon deposit formation. Burns oil @ 1 qt/1k miles, but MUST preserve the catalytic converter. 5k max OCIs.
2. Mostly stock. Called for API SG 7.5w-30 originally (rare spec); later updated to SJ, 5w-30/10w-30/10w-40. Twin-turbocharged, ~120 hp/L @ 0.7 bar boost (maybe more in the future). No catalytic converter. 3k-5k OCIs.
Had a thought or two about going a different route from the usual "any OTS synthetic" or "Red Line/Amsoil/whatever" knee-jerk reaction. Hoping for some informed feedback here.
Mechanically, neither application seems particularly demanding. Also, OCIs will be short no matter what oil is used. That seems to leave plenty of room to focus on other things. For the first app, I'd like something that resists and controls high temp deposits, keeps the engine squeaky-clean inside, and will be extra nice to the catalytic converter. The second app affords much more freedom (less oil burning, no cat to poison), but I figure there's no sense picking a dirty oil if it's not necessary; cleaner can only help.
Based on that, I figure that if I can find low ash oils that still meet demanding specs, they'd probably be good candidates. No sense in a super-robust additive package when a lower-ash one can get the job done with fewer deposits.
Here are some examples from Lubrizol's Relative Performance Tool (link): low ash specs with very high scores for "piston deposits" and "oxidative thickening", while maintaining high scores for wear control.
MB 229.52 and MB 229.71 in the "Passenger Car" section:
MB 228.61 in the "Heavy Duty Vehicle" section:
AFAIK, 229.52 is okay for gas engines; 229.71 may or may not be, but at least one of the oils that meets it also carries gas engine specs. Can't tell about 228.61, but I suspect application #2 would be fine with it either way.
Given all that, am I right to imagine that these would be decent candidates for the applications described above? Are there shortcomings to these specs that might be relevant to the applications as I described them?
1. Completely stock. Calls for ISLAC GF-4 (API SM with starburst) 5w-20. Potential for high heat and high fuel dilution. Prone to carbon deposit formation. Burns oil @ 1 qt/1k miles, but MUST preserve the catalytic converter. 5k max OCIs.
2. Mostly stock. Called for API SG 7.5w-30 originally (rare spec); later updated to SJ, 5w-30/10w-30/10w-40. Twin-turbocharged, ~120 hp/L @ 0.7 bar boost (maybe more in the future). No catalytic converter. 3k-5k OCIs.
Had a thought or two about going a different route from the usual "any OTS synthetic" or "Red Line/Amsoil/whatever" knee-jerk reaction. Hoping for some informed feedback here.
Mechanically, neither application seems particularly demanding. Also, OCIs will be short no matter what oil is used. That seems to leave plenty of room to focus on other things. For the first app, I'd like something that resists and controls high temp deposits, keeps the engine squeaky-clean inside, and will be extra nice to the catalytic converter. The second app affords much more freedom (less oil burning, no cat to poison), but I figure there's no sense picking a dirty oil if it's not necessary; cleaner can only help.
Based on that, I figure that if I can find low ash oils that still meet demanding specs, they'd probably be good candidates. No sense in a super-robust additive package when a lower-ash one can get the job done with fewer deposits.
Here are some examples from Lubrizol's Relative Performance Tool (link): low ash specs with very high scores for "piston deposits" and "oxidative thickening", while maintaining high scores for wear control.
MB 229.52 and MB 229.71 in the "Passenger Car" section:
MB 228.61 in the "Heavy Duty Vehicle" section:
AFAIK, 229.52 is okay for gas engines; 229.71 may or may not be, but at least one of the oils that meets it also carries gas engine specs. Can't tell about 228.61, but I suspect application #2 would be fine with it either way.
Given all that, am I right to imagine that these would be decent candidates for the applications described above? Are there shortcomings to these specs that might be relevant to the applications as I described them?