all you ever

wanted to know about motor oils. 4 stroke that is. HTH Lot of misinformation out there.
Oil Additives & Supplements - Diagnostic News

That's a good basic break down about additives. However far from everything there is about motor oil.

Just read a good article in my latest copy of Boating magazine yesterday. It had one of their writers go through the plant where Merc oil is formulated, tested and made. Really interesting read. I just don't know how to find it on the net and create a link. They were talking about how they formulated their 4 stroke oil and all the why's they they did it. Main jist of it was that the formulated a special mixture of 2 different grades of oil, one part being synthetic then a special ad dative package that inhances it's shear properties that inhances it's ability to withstand long run times under heavy loads and long idle times.

Cray,

I read a similar article by Suzuki a while back. Talking about the main differences between automotive type synthetic oils and oils specifically formulated for marine engines. They ran tests with conventional oils on test engines and the evidence was pretty shocking when the photos came back on what the cylinders and pistons looked like. Nice part about the article was they were not trying to sell "their" oil. Just trying to show the difference between auto oil and formulated marine oils.

Marine engines run at a lot higher RPM rating than say a conventional automobile. These companies formulate their oils to be ran at high RPM's for extended periods of time. I think the marine oils are all really close. The only way each of them could avoid one owner from buying oil from another owner was to manufacture and recommend oils for their motors that other companies don't make or formulate. For example, Yamaha might recommend and sell 10w 30 for all their motors whereas Suzuki makes and sells 10w 40 and so on.

For me, a $15,000 dollar investment isn't worth chancing to oil that might not meet the needs or expectations. Although I don't have a Suzuki dealership any where close to me, the internet has made it easy to purchase the parts I need that I know will do the job. Others might be okay with running their boats on conventional oil and say they don't have a problem. Most of them however have not taken it apart and compared it to something that is running the correct blend and viscosity. For me, I'll stick with the recommendation. It might save me in 5 or 10 years.

All manufactures recommend oils based on testing. Due to federal regulations they have to cut emissions. Burnt oil produces emissions. Weak or no oil severely reduces longevity, effectively turning your motor into a boat anchor. Somewhere there is a balance, and the manufactures have to find it. They work with all sorts of vendors to come up with the right recipe, and hence the recommendation. The article did a great job explaining each additive and it's purpose.