Oil is Oil, which is Oil.
Oil viscosity is the only basic difference with engine oil – well, OK, for about 98-99% of it.
Oil comes out of the ground and it doesn’t matter if it comes from Pennsylvania, China or Mexico. The oil is the same after it is refined from no matter where.
Now with that said, the other 1 to 2% difference is where everyone gets excited about – which is additives and detergents.
Many years ago, they decided to grade oil based off the amount of additives/detergents in the oil, starting with SA (no additives/no detergents), and stair stepping up to current level of SN.
SJ rated oil is not to be used in cars 2001, or newer, SL rated oil is not to be used in cars 2004, or newer and SM rated oil only for cars older than 2010.
I use SA (which is the cheap stuff) oil for my chainsaw blade or for other things that just need an occasional drop of oil on them.
FMJ cars have a minimum rating of SE or SF (depending oil year your car was built). All higher letters supersedes the earlier letters (so we can use SM or SN oil in our cars, without problems).
The only exception (in my opinion) is new camshaft break-in does need a higher amount of ZDDP (which was done away with back in mid to late ‘90’s due to it effecting catalytic converters).
Personally, I don’t see a problem using today’s oil in our cars - if camshaft has already been broken in.
Others disagree with me on that – so in this case, I’m not going to say anything negative about Kkritsilas opinion – for they might be right.
I haven’t any testing data to say who is right, so I’m going to side-step the issue/arguement.
An engine that needs camshaft break-in – does need ZDDP and we are both in agreement with that ( . . . I think).
Diesel oil – again as in gasoline oil is still 98-99% the same exact oil. The difference is the additives and detergents added to the oil – which are quite a bit different than what is used in gasoline engines.
They also use a different rating system – which makes less sense than the SA through SN method.
I’m not happy with the latest diesel version of the current oil (CJ-4), which is not compatible with my ’97 Dodge pickup, with Cummins engine (which uses CE, CF or CF-4 oil) and which requires a high sulfur content, to keep the fuel injection pump lubricated. I will save this rant for another time – before, um, I go postal.
You can use diesel oil in a gasoline engine - I don’t know why you would want to.
Typically diesel oil is more expensive than conventional SN rated oil.
Note: It takes 3 gallon of oil, to change oil on my pickup.
BudW