This pic was taken in my shop a couple of weeks ago. I don't know if my opinion is worth "a grain of salt", but I am definitely "an engine builder". Have been for 40 years. I build for both my own and clients' uses, operate them, and pay attention to how they run and what they look like upon tear-down for repairs. I'm also responsible for their longevity, and durability, so I'm very careful about what spec oil I put in them. I didn't arrive at my current oil-use strategy by guessing. It is very calculated and researched. If you wish to ignore my input, fine. But it was formed over many decades of experience.
Here's what matters about oil. It's not the engine it goes into, but the API Specification. It's the "doughnut symbol" with the two letters. The S* spec is the gasoline spec. Virtually all oils have specs for both engine types. Delo 400 15/40 is spec SI or the 15/40 LE is SJ. Either of these specs require the oil to contain properties for the gas engines the spec was developed for. In the case of SI, the zinc and phosphorous concentrations are a little higher than the SJ, but in both cases suitable for the sliding-surface valve trains the spec was originally developed for.
The current SM spec is for modern engines with catalytic emissions systems that are affected by the presence of zinc and phosphorus in the exhaust. So these compounds are reduced in SM spec oil.
This is the crux of the current problem. The current spec oil SM. Use an earlier spec oil like SI or SJ, and you get the higher levels of the compounds engines with sliding-surface valve trains require. The fact that oils with these specs also have diesel specs is irrelevant. They are very suitable for spark-ignition engines. My "engine builder" says so.
I strongly feel that going to straight 30W has a LOT to do with reducing bearing / crankshaft failures and wear in highly-loaded engines. SyTy and Diesel engines meet my definition of "highly -loaded". The Delo 400 30W is API Spec SH, which is an older gasoline spec, however it's still suitable for use in our engines.
This pic was taken in my shop a couple of weeks ago. I don't know if my opinion is worth "a grain of salt", but I am definitely "an engine builder". Have been for 40 years. I build for both my own and clients' uses, operate them, and pay attention to how they run and what they look like upon tear-down for repairs. I'm also responsible for their longevity, and durability, so I'm very careful about what spec oil I put in them. I didn't arrive at my current oil-use strategy by guessing. It is very calculated and researched. If you wish to ignore my input, fine. But it was formed over many decades of experience.
Here's what matters about oil. It's not the engine it goes into, but the API Specification. It's the "doughnut symbol" with the two letters. The S* spec is the gasoline spec. Virtually all oils have specs for both engine types. Delo 400 15/40 is spec SI or the 15/40 LE is SJ. Either of these specs require the oil to contain properties for the gas engines the spec was developed for. In the case of SI, the zinc and phosphorous concentrations are a little higher than the SJ, but in both cases suitable for the sliding-surface valve trains the spec was originally developed for.
The current SM spec is for modern engines with catalytic emissions systems that are affected by the presence of zinc and phosphorus in the exhaust. So these compounds are reduced in SM spec oil.
This is the crux of the current problem. The current spec oil SM. Use an earlier spec oil like SI or SJ, and you get the higher levels of the compounds engines with sliding-surface valve trains require. The fact that oils with these specs also have diesel specs is irrelevant. They are very suitable for spark-ignition engines. My "engine builder" says so.
hes a great mechanic im sure and a good person