transmission and final drive oil?

[Captainnice]

Anyone using Mobil 1 75W-140 for the gearbox and/or Mobil 1 75W-90 for the final drive? Are these ok to use? Thanks.

[Selden]

It's hard to go wrong with Mobil 1, although when I switched from Mobil 1 75-140 to Amsoil 80W-90 synthetic gear oil, my R1100RT seemed to shift slightly better, and has remained very smooth for the 8400 miles since I last changed the transmission oil. At least where I buy it, Amsoil is significantly cheaper ($10.99) than Mobil 1 (around $18 the last time I looked).

 

The 99 RT is my first BMW, and given the horror stories re oilhead shifting, I was impressed during my test ride, 24,000 miles ago, and continue to be impressed with how well it shifts. Maybe I just got a good one, although I will admit that getting clean shifts requires a good deal more practice and skill than for any of the Japanese bikes in the garage.

[dirtrider]

Morning Ross

 

Lots of BMW riders do use either the Mobil-1 75-140 or the M-1 75-90. I won’t & I don’t in the oilhead final drive but in most other things like the transmission I have no issues using it as is a great gear oil. As Selden mentioned it can improve the transmission shifting (especially cold).

 

[Captainnice]

DR, why don't you use M1 in the final drive? Just personal preference or is there an issue? Thanks

[Captainnice]

Selden,

Thanks for the reply. I saw an analysis online of several gear oils and the Amsoil came out on top. Of course, I wonder about the reporting bias. My RT isn't the smoothest shifter but not bad. Last time I used the BMW oil at $20/quart. Now its $25! Up like everything, I guess.

[philbytx]

Use M1 motor oil in all vehicles. I used M1 75w140 and 75w90 in both my bikes since I had them. However, last year I switched to SuperTech Fully Synthetic 75w140 and 75w90 Synthetic Blend(WallyWorld brand) since I discovered Mobil supplies SuperTech brand oils in the U.S.

 

FYI - I change my Tranny and FD oils along with the engine oil at 6k intervals.

 

 

 

[dirtrider]

DR, why don't you use M1 in the final drive? Just personal preference or is there an issue? Thanks

 

Afternoon again Ross

 

A few reasons I personally don’t are:

 

First being the BMW specified gear oil for the final is 90 weight GL-5. While I would imagine both the 75-90 & 75-140 meet the basic 90 weight requirements it isn’t the gear oil that the final drive was designed around.

 

Next is: the newer multi-weight synthetics like M-1_ 75/90 or 75-140 are mainly blended for newer vehicles with better fuel economy in mind & using high tec seals. That means less seal conditioner than the older spec 80w90 conventional gear oils as tight seals increase friction. With some of the 1100/1150 oilhead final drives having an issue with seeping pinion seals the older conventional gear oil has a better chance of not weeping due to a higher content of seal conditioner.

 

I also don’t think the modern high end synthetics do anything positive for the 1100/1150 final drive crown bearing as the synthetic gear oils are more geared towards ring and pinion gear tooth contact protection than bearing durability. Actually the bearings would be happier running in low additive motor oil. Most of those high level anti-friction additives in high end gear oil are aimed towards gear tooth contact protection. I haven’t ever heard of an 1100/1150 final drive failing the ring or pinion IF all the oil stayed in it and the crown bearing stayed intact. On the other hand I have seen & heard of many 1100/1150 failed crown bearings. On every 1100/1150 final drive I have rebuilt with new PROPERLY pre-loaded bearings (so far) I have not seen a return failure and I use nothing but 80w90 conventional gear oil in the final drives.

 

The above is just my personal opinion so take that for what it’s worth to you.

 

[Captainnice]

DR,

Thanks for the great explanation. I think I still have .75L of the bmw "gold" left from last time so I will use that in the final drive and the M1 in the tranny. Thanks again to you, and to all that contribute to this fantastic user forum.

[Jerry in Monument]

dirtrider,

Thank from me also for a great explanation.

 

Dino goo it is.

[Polo]

Hello Dirtrider,

 

I had heard before about using mineral oil in the FD, I went Amsoil after I was simply unable to find it at any parts store. Any suggestions?

[Polo]

FYI - I change my Tranny and FD oils along with the engine oil at 6k intervals.

 

 

I thought of reserving the question, but it just begs to be asked; why change Tranny and FD oil every 6K, especially fully synthetic?

 

Several manual transmission vehicles I've owned or know of specifically state that their full synthetic transmission oil does not require replacing for the life of the vehicle.

 

I know with the RT is scheduled every 12K with mineral oil? I do it every 24 with synthetic, and haven't had a problem yet. What am I missing?

[Selden]

Strictly out of mental laziness, I decided to change all oils, engine, trans, FD at 10,000 mile intervals. 80,000, 90,000, etc. -- nice round numbers that are easy to remember.

[Peter Parts]

Synth does make shifting slick. But I found a multi-weight -140 seemed to be slower shifting in coldest winter days but not positive about that observation since it is hard to have all your wits about you starting out on a sub-freezing morning.

 

If you use dino (or maybe synth too), consider adding a few tablespoons of Dow Gear Guard or MolySlip.

 

BTW, Tom Cutter has argued strongly for using Castrol in gear boxes.

 

Ben

[philbytx]

To me, it is cheap insurance. It allows me a check for any impending FD or GB failures !

 

75w140 definitely helped smooth the shifting in both bikes. Living in TX, it gets a little warm down here !

[Captainnice]

Just changed them both...used Mobil 1 75W-90 in the rear drive and 75W-140 in the gearbox. Maybe I am imagining things but it sure seems to shift like butter now.

 

The "dealer" had me put in BMW 75W-140 synthetic in both the last time I did it. I trusted him and did it but glad I am back to 75W90 in the rear drive and also glad I am using M1.

 

Thanks for all your advice and for a great forum.

[Jerry in Monument]

Synth does make shifting slick. But I found a multi-weight -140 seemed to be slower shifting in coldest winter days but not positive about that observation since it is hard to have all your wits about you starting out on a sub-freezing morning.

 

If you use dino (or maybe synth too), consider adding a few tablespoons of Dow Gear Guard or MolySlip.

 

BTW, Tom Cutter has argued strongly for using Castrol in gear boxes.

 

Ben

 

I just changed the GB and FD yesterday and followed Tom Cutter's recommendation on the Castrol. It seems to shift much better than before.

 

I've only had the bike 3 weeks and put about 500 miles on it. Probably should have changed it straight off.

 

The GB looked almost new but the FD needed changing. Not horrible but due.

 

I'll probably change them both again in another 500-1,000 just for piece of mind and having a sort of 'gauge' point for my own edification.

 

Will also work on a complete tune-up within the next month.

 

Bike came with all maint. records and it appears to have been very well cared for. I'm the 3rd owner and it's lived its life in the Denver area.

[Selden]

Granted, this white paper is written by an oil company, but it's one of the most comprehensive I have seen: A Study of Automotive Gear Lubes. I was planning to use Lucas 80W-90 gear oil in the FD until I read this report.

 

There are few things as satisfying for a BMW owner as draining the FD oil, shining a flashlight through it, and finding only a small amount of fine, dark residue on the magnet in the drain plug.

[flat_twin]

Granted, this white paper is written by an oil company, but it's one of the most comprehensive I have seen: A Study of Automotive Gear Lubes. I was planning to use Lucas 80W-90 gear oil in the FD until I read this report.

 

There are few things as satisfying for a BMW owner as draining the FD oil, shining a flashlight through it, and finding only a small amount of fine, dark residue on the magnet in the drain plug.

 

That IS a happy moment isn't it? And I thought it was just me. LOL! After losing a final drive while on vacation, I change the rear drive oil with every motor oil change too. I use the inexpensive regular 90 weight dino oil

[Jerry in Monument]

Granted, this white paper is written by an oil company, but it's one of the most comprehensive I have seen: A Study of Automotive Gear Lubes. I was planning to use Lucas 80W-90 gear oil in the FD until I read this report.

 

There are few things as satisfying for a BMW owner as draining the FD oil, shining a flashlight through it, and finding only a small amount of fine, dark residue on the magnet in the drain plug.

 

Exactly what I was hoping to find and what I did find this past Saturday.

 

I figure the few extra bucks I spend on changing the GB and FD every 6k, will hopefully prolong their life and my enjoyment.

[philbytx]

Ok..Amsoil came 1st.

 

But, #2 was Mobil1 , a good lube and available pretty much everywhere!

[Selden]

I figure the few extra bucks I spend on changing the GB and FD every 6k, will hopefully prolong their life and my enjoyment.

I'm not sure there will be any cause-effect relationship, but at least 6K intervals will give you early warning if your FD starts to go bad.

[Jerry in Monument]

I agree that there may not be a cause and effect, but doesn't mean there won't be either. Better safe than sorry.

[4wheeldog]

Ok..Amsoil came 1st.

 

But, #2 was Mobil1 , a good lube and available pretty much everywhere!

 

Plus, the tested was sponsored by amsoil. There are so many Amsoil promoted tests out on the web, I wonder if they actually use a bottle off the shelf, or supply the "Special" stuff?