Steet

I have 2 new K & N that I ran on my boat for 2 weekends and I could not tell any noticeable difference.
I put my stock Merc's back on. If interested let me know. I have them in the plastic in the cartons for half price of new, shipped to you free.

impulsive

????

mcollinstn

Do not run a conventional multi vis in a performance boat motor. Multi vis oils have complex additives with viscosity enhancers and a mix of oil stocks with different volatiles and such. In a high load application (look up marine performance in a dictionary) the multi vis will soon "boil out" the lighter stocks and leave the gummier heavy stocks.

Merc oil is not a typical multi vis. It is a two stock straight grade. Good stuff. Designed for what marine motors need.

As far as synths, Merc does not recommend them. I can come up with no technical reason why they advise against them. Synths are overkill for most automotive apps, but are great for a marine motor.

But Merc oil is good stuff.

RedDog382

Can't speak for Mercury, but Sterling recommends Mobil 1 for their mills.

Lmarth

I agree withe Red Dog. Sterling rebuilt my 800SC"s and recommended Mobil 1. That was 100 hours ago and they run like a top.

muffman

I heard not to use the synthetic because the roller lifters have a tendency to slip on the cam rather than roll creating flat spots on the lifters. It's just what I heard.

mcollinstn

The roller lifter warning is purely a wives' tale. Bogus info. Won't happen.

Synthetics ARE slipperier under EP (extreme pressure) situations, but under no circumstance will they CAUSE a roller lifter to "hydroplane" if the correct viscosity is used and the cam and lifter are functioning properly.

EVERY automotive primadonna manufacturer has tried to proclaim their own LIST of lubricants to be the only ones approved for use in their vehicles. One by one, they have had to admit that stright synthetics such as Mobil1 are approved and are, indeed, superior lubricants. Mercedes now has a 10,000 mile oilchange interval (it varied a bit according to whether the computer senses light freeway driving or lots of stop and go and high rpm - there is a service indicator that tells you when to go for an oilchange) - BUT the long interval only applies IF you use SYNTHETIC lube. Otherwise the change interval is shorter.

Corvettes come with synth.

All OHV motors being manufactured these days use ROLLER CAMS. And most of these use fairly light valvesprings. If a lifter was going to hydroplane, it would be on a Northern Coldstart pickup truck motor (light valvesprings, heavy viscosity when cold). It just ain't happening.

Performance motors with typically much heavier valvesprings and more cautious owners who observe proper warmup procedure will be on the other end of the "likelihood scale" for lifter skiing.

muff, be sure to tell your sources that unless they can prove that the world is flat, that they are wrong about lifter skiing.

formula31

All very good info. Id still like someone to explain to us the break-in issues with synthetic and how the oems get away with it in car engines.

Dock Holiday

They look great, no problems but I did not see any improvements in performance!

jpclear

I would like to thank you, mcollinstn for your post. I was kinda upset with some of the other input but elected not to get involved. I think you said it all very well and I agree completely! --- Now to address formula 31's query. My understanding is that most performance engine builders like to finish cylinder bores with a light crosshatch and allow the rings to seat or wear-in during a break in period with a good quality oil that is not TOO slick. Most of todays OEM engines are born with real smooth bores and hard rings that really fit, so they can put the real slippery, heat and wear reducing stuff in right from the "get-go"; not much need for the break-in/wear-in with the more friction and wear permitting fossil oils. (I bet I really put my foot in it now!) --- Jer