powerqrudy

you know i switched like 4 years ago..I can swear I picked up 1 MPH but is could have been from other stuff also ?? who knows.

I drained my fluid after the year was over and like the fluid that came out half was water !!!! fixed the problem and it (the drive) worked great ..till some one stole it...

Hydrocruiser

I talked to a mechanic about this at a local marina and he told me he knew a guy who ran Royal Purple Straight Weight 50 Synthetic Oil in the drives and 0W-40 Synthetic oil in the engines.

Prior to this he ran 20W-50 conventional oil in the engines and 75W-90 conventional gear lube.

Results...picked up 5 MPH....drives were fine last he heard....never a probelm with the 454 engines. It was in a 38' Scarab. Might be good for a Bonzai run?

I have used 10W-40 in my 350 magnums without a problem and picked up a mile an hour over 15W-50. But I never thought about going to a straight weight RP oil in the dirves...but obviously it can be done. Wish we had more data to go on.

launchit

First of all, thanks for the warm welcome. It's been a long work week.

I have some comments regarding oil viscosities. There are a few types of viscosity scales, SAE gear and SAE engine are two of them. 75W-90 SAE gear oil is the same viscosity as SAE engine 40 or 50 engine oil, however your drives call for an extreme pressure (EP) type gear oil SAE 75W-90 with the protection for the gears. SAE engine 40 or 50 grade does not have EP additives and will not protect your gears as good as a gear lube with EP additives.

As for switching from a 20W-50 to a 10W-40 --- There could be some fluid friction advantage by using the 10W-40, however, when talking engine oil to engine oil, viscosity is not the only factor to look at. Additive type and content, base oil type and quality, and where the oil sets on the cSt viscosity scale. Kinematic viscosity is measured in cSt, for example a SAE Xw-30 has a range the the 30 part measured at 100 deg C from 9.5 to 12.5 and a 40 grade at 100 deg C has a range from 12.6 to about 15.5 (sorry I'm doing this from home without any reference books but it's close). Anyway if you have Xw-30 that has a cSt of 12.4 and a Xw-40 that has a cSt of 12.6, then there will most likely be no fluid friction gain and any gain at all would have to come from differences in the base oil or additive content and amounts. When I was in CA., I worked with a Blown Gas Hydro and a Blown Alcohol Hydro to gain as much reduction in viscosity for reduced fluid friction without reducing wear protection. The proper additive content and type of base oil had about the same to do with the reduction in coefficient of friction as the reduction in viscosity.

I know, most likely more than you want to know on a Friday after work. I just thought you might like to know more about oil than the average guys. (protect your investments)

Sincerely,
Kevin Dinwiddie

launchit

BTW,
Anyone see what's on page 31 of the May issue of Powerboat?

Kevin Dinwiddie

Hydrocruiser

A picture of Troutly modeling Apache' swim trunks?

Hydrocruiser

Yes what you are saying has been debated on Bob's site for a decade...bottom line......everything is empirical.

Yes one needs an EP additive system in a drive...at least GL-4 or gears will wear quickly.

In my books:
Amsoil
Mobil-1 Goldcap
Redline
Royal Purple
Torco

Too close to call on who's the best but they are all significantly better than conventional oil.

Anything said is speculative at best. You would have to test all in drives or engines to convince me one is better than another.

Personally I like Moly a lot. Redine; Torco; Royal Purple and now Mobil-1 Goldcap put a good dose in.

Why is Amsoil's site critical of Moly in Royal Purple? They say it is a powder that Cummins dosen't like etc....

Well all additives are powders of one sort or another be they antimony...Molybedium Sulfide; ZDDP; Calcium; Phosphorous etc...

I just don't get it..they are EP additives...why dosen't Amsoil use moly or have they now begun to with the new mandates where ZDDP is being phased out? Benz and Porsche' are fine with moly in their aluminum engines ya know.

From what I read tonight Torco Synthetic Gear Oil has my full attention at GL-6 and since Mercury Marine uses it in #6's ...if the shoe fits..

launchit

To each his or her own opinion, however GL-6 is obsolete and has been for quite some time. I believe that it's because the test could not be performed the same every time and was considered unreliable.

KD

Donzi Corleone

Hydro, I like staying with the Merc stuff afterall Im running 300X sportmasters O/B, but sometimes I wonder if there is better stuff out there. Afterall total protection is something Merc may not want. Remember their biz is made up of me buying parts and gears. So they make something good ,but not the best it can be. I still use the Merc HP stuff, but thinking about something totally synthetic. I run hard and have had several gear failures on 2 year old motors, so im thinking about trying something different just and see what happens

Hydrocruiser

In many cases a GL-6 "label" is applied if the product significantly outperforms GL-5 requirements.

Hydrocruiser

Give Amsoil or Torco a try. Both PAO's.... both great products..both tested in outdrives...let us know what you find.

Here is my take on what is the best drive oil:

Mobil-1...users like it..easilly available...PAO

Amsoil...New formulation...PAO...Good company

Royal Purple...not PAO but repels water best

Torco...PAO...Mercury uses it the #6's....wow

Redline....75W-140 thick and may foam due to air trapping
use 75W-90 in my humble opinion.

Alisyn....PAO...good formulation...loyal users

Mercury HP....Semi-synthetic limitations but very good

...and the winner is...the one you pick!