View Full Version : TR2/3/3A 70/90 Gearbox oil and Synchros degrading?

06-25-2014, 03:34 PM
I drained the oil from the TR6 box in my TR3. There seemed to be lot of tiny brass like flakes in the old oil which I assume are from the synchros. Is it normal to have some synchro swarf in old oil or are the properties of the 70/90 gear oil degrading the brass synchros.?
I've heard that GL4 gear oil does not affect the synchros but that it is difficult to find.....up here anyway. Apparently Redline makes a GL4 70/90 gear oil. Anyone using the Redline and did they find any difference in the way the gears shifted? I've also heard that in older gearboxes the Redline tends to leak somewhat?

06-25-2014, 04:39 PM
I use and like Redline's MT90 (https://www.redlineoil.com/product.aspx?pid=46). Makes both my Triumph boxes, a Muncie, and a Top Loader shift smoothly (up and down and even when cold). I've read (here) that some find that it leaks past seals more easily than what they previously used. I really don't think it does.

Geo Hahn
06-25-2014, 04:46 PM
I use the Redline & have some small leaks -- but I doubt I can blame to oil for that.

Some 'gold dust' in the oil is not unusual in my experience. How much is 'a lot' I couldn't say.

06-25-2014, 04:56 PM
The "gold flakes" are not caused by the oil degrading yellow metal; because the degraded metal is black and powdered very finely.

IMO they are also more likely to be from the thrust washers than the synchro rings. Hopefully, you are just seeing some early "bedding in" that will stop.

I likewise use Redline MT90, and found that, for me, it significantly improved the synchro action. No evidence that it increased leakage, but I also changed the input and output seals (an easy task with the box out of the car) when I converted.

Another good option is Valvoline 20W50 Racing oil. Certainly a lot cheaper than the Redline, and worked well for me for many years. That's what I used before switching.

06-25-2014, 06:02 PM
If you have an OD, that increases the chances that the "gold" particles are from thrust washers.

06-25-2014, 07:42 PM
I doubt you have much to be concerned about. My gearbox (OD unit) was rebuilt about 14 years/ 11K miles ago. For unrelated reasons, I have probably changed my gearbox oil 3 times in the last 4 years Went from GL4 to SAE30 oil, to Redline MT90, to 20W-50, finally back to GL4. Each time I noticed a gold metallic shimmer in the drained oil. Honestly, for all I know, oil off the self may have the same characteristic.

So far, gearbox still performs flawlessly and I've had no catastrophic failures. So, I while I was initially concerned, by this point I am satisfied nothing is wrong.