Joey and Bobby,
 

Thanks for the info. Now I'm a bit worried. I hope the guy at least knows how to do a rebuild!

Guess I'll find out soon.

audacity,

I know you've done extensive testing and stuff, but I've been told that while Merc Hi-Perf is synthetic, it uses a different base composition for the simple reason that it will absorb water and still perform. This was a requirement of the Merc spec cause not everybody changes drive lube as often as us guys and they didn't want the headaches of water intrusion warranty concerns.

The water-absorbing makeup gives up some desirable qualities in order to get it to absorb the water.

Feel free to correct me if I am mistaken. We are all here to learn.

this may very well be the truth about merc lube!!!

all synthetics are not the same!

for me this would be a 100% moot point...we change the oil every weekend, even on our pleasure boat...we always pull the top cap off the drive to inspect as well...very easy to do and it speeds the oil change up big time.

M1 in everything, never a problem. Some new cars come with synthetics, the Vette is one.

Great thread. The "OIL" issue has allways been a good one. I have been researching the synthetic oil issue for a while and think that is the way to go for my engines. I have pre-lubers to help with the long down time beween starts. This post by Audacity does make me question using sythetic in my drives

I don't mind changing the oil in the outdrive ever 25 hours with the engine oil........but after every time we take the boat out........that is just not practicle.

Sounds like I should stick with the Merc oil for the drives.

What I was told is that Synthetic oil may allow the bearings on High HP blower motors to "slide" rather then "roll" creating flat spots on the bearings.....

MODVP

The only rolling-element bearings in an auto/marine I/O engine are the roller lifters and roller rockers (if it has them).

Those bearings will be under the same loads and conditions in a blower motor as they would be in a NA motor.

As far as roller lifters flatspotting, the Heavier or Thicker the lube film, the higher the chance of stalling the roller. AND it is more apt to occur at low rpm with heavy lube in a cold motor. One of synthetics' biggest advantages is its resistance to cold weather thickening.

The tips on roller rockers have been shown by high speed camera to either "not roll", or "roll backwards" at certain rpm. This behavior is more due to harmonics in a dynamic spring-loaded condition (think of those Gee Haw sticks where you make the propellor spin different directions) than any sort of lube film breakdown.

I notice your name MODVPSST. Your Merc outboards have rolling-element bearings all over them. The crank bearings, the rod bearings, all of them. I would recommend synthetic non-castor 2 stroke lube for you to run in them as well.

Lubricants are always a great topic! I will try to comment on a conversation I had with GM lubricant product specialist, actually she had her phd and was provided to speak at a customer's meeting where many oem were asked to make lubricant presentations/recomednations. She has writen a few papers and are all way above the layman's level of comprehension. One of the main reasons she felt synthetics were of a benefit in passenger car operation was that the oil has the ability to "re-juvenate" itself, at least in her reference to Mobil1. Apparently when a normal crude oil takes on moisture some degree of permanent damage occurs to the additives in the oil. As I recall, with Mobil 1 the damage is not permanent. There were other benefits also associated with the Mobil 1 where she advised me that in my high performance application it would be worthwhile to make the switch...and I have. As a side note, the intent of my questioning was not to obtain her opinion on the best synthetic but rather comparing Mobil 1 to crudes.

Bob,
She must've been pretty hot, eh?

MC.... What you say certainly makes sense.... I am relating what my engine builder has told/shown me... I do use Mobil 1 in my HP500.... I use a product from Alisyn for my 2-stroke... for anyone interested they have a website Alisyn.com & I highly recomend thier gear lubes as well as thier 2-stroke product... Take a look Alisynlubricants.com... I think... it might be Alisyn.com... I'll check.... but thier good people & I can't say enough about thier gear lub's....