I run Valvoline VR-40 in my engine.

I was thinking of running REDLINE SHOCKPROOF OIL in my drive I hear it's great. but what weight do you run? Heavy, medium or lightweight?????? I seen it on www.fishermotorsport.com

10W40 AMSOIL SYNTHETIC
 

I change the oil and filter every spring and change the filter and add a little around July 4. So far so good!:D

Just a thought on running synthetics in the drive.
Is the Merc drive lube a synthetic blend?
Do the other synthetic lubes mix with water?
Does Merc lube mix with water?

Just the questions that ran through my head before I made my choice;)

Royal Purple, motor with preluber, and out drive. I did some tests and found a 12 degree difference with the RP in the outdrive. It ran cooler! It runs longer and stays cleaner. Water seperates faster than the dino stuff.. just my .02

I run the dino stuff for break in.. maybe 10hrs.

Dick

formula31, no I wouldn't recommend using synthetic diring break in. In fact I'd wait until about 100 hours, then do it if you were so inclined.

I still think that the question concerning the benefits of synthetic oil, revolves around the outdrive versus the engine...

YES - Mercruiser Hi-Perf Drive lube will absorb water. It was formulated to do so.

Most drive lubes, synthetic or otherwise will not absorb water, but will "milkshake". If you let them sit, the water will drop out of suspension and some parts near the bottom will be susceptible to rust.

Do not break a motor in on synthetic. 10k miles on a car or 25 hours on a boat before swapping to syn lube.

Probably wouldn't hurt to run a fresh drive on Merc HiPerf for ten hours or so at 80% or less before swapping also (although I have always gone straight to synthetic in the drives).

Ok, so how do the new engines that have synthetic in them from the start work? Do they have special rings or honing that allows this?

Ok I attended a G.M. Tech College program. I have spoken to may builders and engineers. They said there are many FALSE rumors about oil. Synthetic Oil is better for high rev rpm's and heat but normal driven motors don't reallt need it. As far as break in time. NOTHING was wrong with running sythetic's It's all in that "doughnut symbol that is on the back of the quart of oil. it all reads the same n tests OK as far as GM is concerned for motors.

They did say some transmissions and rears don't seem to like synthetics. So i think this all comes back to this? What came first the chicken or the egg?
:p 2 feet of snow here In Philly n counting

Mobil Delvac 1 - I have friends that used the Mobil 1 and switched to the Mobil Delvac 1 and like it much better.