is mobil 1 75-90w ok for tranny/rear drive

[barncobob]

can only find mobil 1 and royal purple. cant find a straight 90w.

[philbytx]

75w90 is spec'd by BMW but some on the board (including myself) run 75w140 in the tranny and rear drive.

[barncobob]

if 75-90 is specified, what is the advantage of using the heavier oil?

[realshelby]

In my '04 RT the heavier oil greatly reduced the noises associated with shifting. Probably no other advantage.

[BucksTherapy]

75W140 in the final drive seems to work well.

 

In the tranny I have switched to Redline's Shockproof Heavy which behaves like 75w250. It has significantly quieted the tranny and made shifting smoother.

 

I have tried a number of combinations with different results but these two work the best for me.

[Rags]

if 75-90 is specified, what is the advantage of using the heavier oil?

 

I was in 100+ temps for 3 days and my new 75-90 gear oil sounded like bolts rolling in a tin can. I think the old spec is 75-140. I wish I had them put in the old spec.

[keithb]

I just changed my tranny fluid and put in Valvoline 80w90 synthetic. The mechanic I use for some service recommended the 75 weight to quiet the shifting. Since I had already purchased the 80w90 I decided to use it. Next fluid change I will try the 75 weight.

[ronest]

Originally, I used a non-BMW synthetic and then switched to a the BMW synthetic on a R1200C and noticed that the transmission was warmer to the touch using the non-BMW compared to the BMW lubricant. I never measured the heat difference with a meter, but I figure that the less heat the better. I prefer to stick to factory lubricants after my experience.

 

RD

[Global_Rider]

can only find mobil 1 and royal purple. cant find a straight 90w.

 

Bel Ray Hypoid 90. All I've been using since 1991.

 

I spike it with 5% Dow Corning M Gear Guard lubricant for the final drive of my oilheads.

[Rags]

I just changed my tranny fluid and put in Valvoline 80w90 synthetic. The mechanic I use for some service recommended the 75 weight to quiet the shifting. Since I had already purchased the 80w90 I decided to use it. Next fluid change I will try the 75 weight.

 

Its the first time I heard someone suggest a lighter oil would quiet the transmission.

[keithb]

As I recall he mentioned smoother shifting as well.

[Bruce Barrow]

BMW 75-140 synthetic is the way to go. Heavier weight=quieter and smoother shifting especially when fully warmed up. I changed my 99 RT a few years ago during a heat wave of 100+ and immediately noticed the difference.

Ride safe.

 

Bruce

[Global_Rider]

if 75-90 is specified, what is the advantage of using the heavier oil?

 

Or more importantly, what are the disadvantages of using a heavier oil?

[Chubber]

In the tranny I have switched to Redline's Shockproof Heavy which behaves like 75w250. It has significantly quieted the tranny and made shifting smoother.

 

+1 for Redline Shockproof Heavy. I have used it for years and find that it really makes it quiet and shift easily. Winter or summer, even up north. Just don't get any on your pipes, it is even stinkier than regular tranny fluid. That is how you know it is good!

[Ebbo]

I tried 75/140w oil years ago in an old airhead, it was murder when cold, gears were very stiff and extremely clunky. Once fully warmed up it was great, but I dreaded the gearbox cooling down again…

 

I think if you live in a very warm place, its worth experimenting with, no good in the UK IMHO

[Paul Mihalka]

Using experience from a airhead gearbox for the R11xx bikes is almost as bad as trying to apply experience from a 1950 BSA .

My personal experience: On the R1100 BMW 75/140 synthetic makes it shift nicer. Redline Heavy (75/250) makes it shift even nicer, but gets a bit stiff around freezing temperatures for a few miles.

With my R1150 I am using Amsoil 75/90 synthetic since I have the bike, because it is available where I work. It shifts so nice that I don't plan to try anything else.

[Ebbo]

Sorry, you’re right; it’s not fair to compare an 80’s 5 speed clunky gearbox with and 90’s 5 speed clunky gearbox