Holdec, first off, if the oil the original owner was
using was API-SL then it was not actually "non-detergent" as then it would be API-SA. The biggest error right off the bat though is if it was designated only for gasoline engines only. The "S" in the API rating indicates "spark ignition" and is for gasoline engines. A "C" in the API rating indicates "compression fired" and refers to diesel engines. Often diesel crankcase oil carries both diesel rating and gasoline rating. On the other hand gasoline engine oil will indicate use in "gasoline engines only" as many as 5 times on a single bottle. Another dubious choice would be why he was using API-SL in any engine when that designation has been replaced literally decades ago now up to API-SN for gasoline engines. Lastly, straight 30 weight, and there is high detergent 30 weight diesel oil, even if acceptable would not be preferred.
using was API-SL then it was not actually "non-detergent" as then it would be API-SA. The biggest error right off the bat though is if it was designated only for gasoline engines only. The "S" in the API rating indicates "spark ignition" and is for gasoline engines. A "C" in the API rating indicates "compression fired" and refers to diesel engines. Often diesel crankcase oil carries both diesel rating and gasoline rating. On the other hand gasoline engine oil will indicate use in "gasoline engines only" as many as 5 times on a single bottle. Another dubious choice would be why he was using API-SL in any engine when that designation has been replaced literally decades ago now up to API-SN for gasoline engines. Lastly, straight 30 weight, and there is high detergent 30 weight diesel oil, even if acceptable would not be preferred.