Sorry I am asking this cause I see tons of post on oil most of which are too technical for me. (too much information) Just looking for some quick reccomendations. I am at about 100+ hours on my 500EFI's and used nothing but the merc oil. 25/50.

I need a good oil that is easily available at K-mart wal mart murrays ect. I have seen some people switch to synthetic. Not sure if this would be right for me.

I dont change my oil a a religious schedule, I check it and when its gets a little dirty I have them change it. keep this in mind too. ON my old blower engines I used a kendall oil because that is what the engine builder reccomended.

I dont think I need to pay a premimum for the merc oil but will if it is the best.

Thanks

I'm sure Merc doesn't have their own refineries, it's made by someone else. I'd say any premium oil would work. Probably stay in the same weight, or thereabouts.

BTW, I ran dino oil in one of my engines, and synthetic in another, I didn't see any difference in either performance, or pressure of the oil. I was hoping the syn would calm down some of the frothing I think I get in my oil at a high speed run.

What is concidered premimum? Pennsoil, mobile, castroil, ....

Mobil1 (sythentic) 15w50 is perfect for that engine.

thats what they always put in mine

I would vote for a premium 20-50W, especially in warmer water or temps. We don't use the synthetic Mobile one oils, we have our reasons, but we''ll keep those reasons to ourselves.
Kendall, Valvoline, Red-Line, Mercury 25-40 or such should work just fine.
Most real oil issues and problems in marine hi-po engines begin with improper oil pressures, improper oil temperature maintenance and engine clearance and plumbing issues. Don't expect any oil made to solve these problems or cure them. Get everything set up right in and on the motor, then just use good oil, use good service and maintenance methods and the rest will take care of itself.

Ray @ Raylar

mobil 1 v-twin 20W50...ran it in my 500 efi's all last year, seemed to loosen them up some and keep the pressure up where it needed...

Guy's He admits ,Since he doesn't change the oil religiously I doubt he will buy synthetic.

I use Val racing St 40 or like Ray says the 20W50,but you really need to change it more often

I agree 100% recomend straight weight SAE 40

other then the merc 25/40 I dont like to use multi grade oils in marine apps