How does an engine manufacture determine what weight engine oil and type to use in the engines they produce? Ie: 15w40 or 10w40 ect.....

Is there that big of a difference between 5w30 and 10w30, or is one manufacture engine oil that much more superior than the next guy? I would think the additives in the oil and the amount of the additives makes a difference between one oil and the next?

I guess what I'm trying to say is, Mercury has a brand of oil that someone makes for them, and Mercury (or whoever) has an engine warranty to keep and a reputation to keep with there customers, so they want what is best for there engines ... right? Do the oil manufacture talk with the engine builds and manufactures to determine the stress loads of the particular application? Oil "A" is better than oil "B" because XYZ......ect.

Just some thoughts that I've been thinking about....any idea's would be great.

Thanks

I have had great luck with AMSOIL. On the other hand, Mercury works with who ever they recommend to have oil made to thier specs. They know what is best for thier engines. If the engine is under warranty I would run thier oil. Just to make them happy if something happens. If not I would contact your local AMSOIL dealer.

I thought this would have been a hot topic??? Well, thank's for not skunking me Screamin' Seaman'!!
If just running the Mercury Oil .... I tries Mobil1, but I had some issues.
Thanks for the reply!!

No one is trying to skunk you, it was a hot topic. Sit down when you have a month of reading time. alot of good info, all you will ever need to know.

http://www.offshoreonly.com/forums/s...&highlight=oil

If you change oil frequently it doesn't matter. today's oils are far superior to your daddy's oil of olden times. Hel even the recycled oils found at Advance Auto is better than our dad's.

Synthetic will last longer and is more resistant to heat. But if you change frequently it's irrelevant. If you don't, invest in synthetic.

Yes Mercury buys from elswhere and pays for the right to slap their labels on the oil and other priducts. Remember, it's a capitalistic society. The warranty comment in the frivolous handouts calle downers manuals, are the carrots at the end of the proverbial stick to "pursuade" you to buy their products (read more collateral revenue). Hence the disclamiers of appropriate alternative product weights.

I change every 20 hours, so it really doesn't make too much of a difference. Running Valvoline Racing straight 40.

That is good oil. In the silver bottle it still has extra zinc in it and is really good for the older style flat tappet engines.

The best oil is the kind you rub on them purdy gals on your boat and I'll never forget the time my Dad came home late and drunk, Mom had some dog food in the skillet with bacon grease poured all over it soaking to feed the dog the next morning. The next day Dad asked Mom "what kind of hamburger helper was that you cooked last night"?

how come a 5.0 efi volvo penta has to run 30 weight sythetic but a similar motor by mercury would not have to run synthetic? arent they both pretty much gm blocks and what not?