UOA for Transmission and Differential ~50k miles - The Unofficial BMW M5 Messageboard (m5board.com)

ard · 16th April 2006, 08:21

If anyone is interested- ran UOAs on the 'factory fill' Tranny and Differential fluid when I changed them last week.

Replaced with BMW fluids. Noticed no change in shifting. But did feel better about it....

A

Beamer_usa · 16th April 2006, 08:26

Thanks for the info. from Blackstone labs. I also changed my fluids @ 48k with the OE fills, no difference other than piece of mind.

DavidS · 19th April 2006, 11:12

Thanks for starting this thread, Ard!

I also changed gearbox fluid some weeks ago. Great to get some comparison data from you!

The car has 57996 miles, and the transmission oil had 30540 miles. (The oil was changed three years ago, so this is not the run in oil.)

From Blackstone:

Aluminium 60
Chrome 0
Iron 53
Copper 43
Lead 1
Tin 1
Molybdenium 2
Nickel 0
Manganese 7
Silver 0
Titanium 0
Potassium 1
Boron 196
Silicon 13
Sodium 13
Calcium 16
Magnesium 1
Phosporus 486
Zinc 23
Barium 1

Sus viscosity @ 210 deg F: 49.2
Flashpoint 435 deg F
Water 0%
Insolubles: Traces

These numbers are very similair to Ard´s numbers, except Ard´s have higher
Manganese, Zinc and Barium levels, and higher insolubles. Only natural as his sample was from the original oil (I assume after the 1500 mile run in service gearbox oil replacment? Or did the dealer cheat...?), and my sample is from oil that was replaced once before.

The gearbox used to be difficult to shift into 1st, 2nd and 3rd gears when cold.

Having read posts by others using Syncromax for some years, and being tired of the gearbox to the point of being willing to buy a new one, I decided to put Royal Purple Syncromax in. This had a huge effect on shift quality when cold. I would highly recommend Syncromax to anyone with a stiff gearbox. So far so good!

David