I am planning to run in my new Truetrac diff for about 3,000kms with a mineral based oil, then switch to a synthetic rated to withstand the higher temperatures of the circuit before I head out to the track again next year.

I understand that Harrop and the diff manufacturers always recommend a Mineral based oil for the entire time due to the helical gears, but I have also heard that Mainlube has used their synthetic in many Truetracs with no Open Wheeling either.

With my stock LSD diff with the clutch packs (now 180,000kms old and countless circuit days) I always used synthetics from Castrol, Amsoil, Nulon or Royal Purple often adding extra additives like Amsoil Sliplock, and very often the Mainlube Synthetic too.

Any recommendations?

I's also like to know peoples thoughts on this and if anyone found more wear n tear with certain oils.

How often do you plan on changing the fluid? If you stick to what Harrop recommend then I would stick with mineral, but synthetic makes sense for prolonged use.

I don't think there would be an issue running mineral as long as you change it regularly. Perhaps after every two or three track days?

mineral all the way,KAAZ diff oil in mine.

How often do you plan on changing the fluid? If you stick to what Harrop recommend then I would stick with mineral, but synthetic makes sense for prolonged use.

I don't think there would be an issue running mineral as long as you change it regularly. Perhaps after every two or three track days?

I usually change the diff oil every 2 circuit days or 7,500kms or so.

My concerns with using a mineral based oil all the time is the ability to withstand the higher temperatures of the circuit on slicks with an 1800kg car.

Will use a mineral for the initial run in though. Any recommendations for a Mineral based oil?

Have been black flagged too many times on the track by overheating my diff oil and am over it. This is why I want to use a synthetic.

I still have the after market catch can fitted from the breather.

Truetrac should sort most of my problems hopefully. My old diff was dead.

Only negative I can see with synthetic long term is possible slipping, but users of Mainlube Synthetic have not reported any problems.

Was hoping I could use something like Royal Purple Maxgear 85W 140 after the run in with some extra additive (like Sliplock).

To be honest, I don't have any long term data on your exact situation so it's hard to say exactly how it would go.

If the viscosity is correct then I can't see how running a synthetic oil would hurt it. Particularly with the additives you speak of

I used mineral for 1000klms, then switched to the Amsoil and have not had any issues.

I know drag racing is different to circuit but the car has probably seen 30+ burnouts and passes

I have been pm'ed by Aaron at mainlube who would like to test the Amsoil.

I have almost done 10,000 on the Amsoil so will be dropping 100ml to send to Aaron aswell as 100ml of Engine oil as he has offerred to test both at no cost.

This also will give an indication of how well the oil is performing and what type of service intervals will be required.

Once the testing is complete I will post up the results.

Nice one George

I used mineral for 1000klms, then switched to the Amsoil and have not had any issues.

I know drag racing is different to circuit but the car has probably seen 30+ burnouts and passes

I have been pm'ed by Aaron at mainlube who would like to test the Amsoil.

I have almost done 10,000 on the Amsoil so will be dropping 100ml to send to Aaron aswell as 100ml of Engine oil as he has offerred to test both at no cost.

This also will give an indication of how well the oil is performing and what type of service intervals will be required.

Once the testing is complete I will post up the results.

What mineral oil/ viscosity rating did you use for the first 10,000kms?

What mineral oil/ viscosity rating did you use for the first 10,000kms?

1,000 only and I 'm not sure what Con used but it was a Castrol mineral oil.

Edited October 5, 201214 yr by rednose