And I do recall reading about some additive that diesel engines need for soot control, maybe not being good for gas engines. Who knows.
Yeah. I have "heard" that too. It's another old wives tale IMHO. All of the diesel "rated" fleet type oils also meet current gasoline engine API ratings. I know of no one that has EVER had an oil related failure in a gasoline engine from using and CD/CE/CF/CG/CH/.........etc oil that also was additionally rated at whatever the current gasoline rating was.
Additives that help to keep soot in suspension do not make the oil any more "detergent" than any other gasoline (only) rated oil.
And yes. NO ONE should EVER "flush" any old engine by diluting the oil with kerosene, diesel, gasoline, Marvel Mystery oil, ATF, Seafoam, Super Secret Owl Snot, or any other snake oil.
That could absolutely cause sludge to break off and clog the oil screen.
If it broke off AFTER the oil filter in an oil passage supplying a main, rod or cam bearing, you could starve that bearing and cause a bearing seizure.
As usual, (And I just LOVE oil threads!!!) these threads ALWAYS end up being:
"Here's what I use and I have never had a problem........."
Back the OP's question......
what motor oil should I use
October 2nd, 2017, 06:40 PM
My 1996 4.3 l mercruiser calls for an SG grade oil.
If you do not want to use what Mercruiser currently suggests using, you can safely either use any oil on the the chart Bruce posted above........OR you can just about use any oil on the Autozone or Walmart shelf (near the correct viscosity as required)
Understand 0W30, 5W30, 10W30
synthetic oil IS SAE 30w oil at 100C............ 0W40, 5W40, 10W40, 15W40, 20W40 and 25W40
SYNTHETIC IS 40 wt oil @100C
Synthetic oils DO NOT thicken when cold like NON-synthetic straight wt oils do.....which is why you might want to use them in very cold temps all the way down to -30F.......although if it's -30F, your engine will start and run great......your boat will be literally FROZEN IN PLACE and if you're raw water cooled, the engine will over heat quickly......the raw water pump won't pump solid ice!!!!!
NON-synthetic 5W30, 10W30, 15W40, 20W50 etc...... ARE 5wt, 10wt, 15w and 20w oils (respectively) and use viscosity improvers to get to the higher visc at 100C
When the VI-improvers "wear out" the oil will become thinner. (because they ARE thinner without the VI-improvers)
Cheers,
RIck