How often to replace redline oil in transaxle

[GTVeloce]

I was thinking the other day that I haven't changed the oil in my 75's transaxle for some years (2012 I think) and it has done quite a lot of clicks since then. I am using Redline Lightweight Shockproof. What's the general consensus on replacing this? I have heard of racers just passing it through a sieve and then reusing it. This is a road car so it doesn't get hammered too hard.

If it wasn't so expensive I'd just change it but shifting quality is still good - if it aint broke...

[bonno]

Hi GTVeloce
IAW maintenance schedule the gearbox oil is to be replaced at 24,000 kms or 18 months (refer P16 Haynes workshop manual). I consider this a  bit excessive and I replace it every 5 years or 50,000 kms on my Alfetta GTV.

[Colin Edwards]

Have Castrol Syntrax Universal Plus 75W-90 in my 75.

Castrol, Shell and probably a few other manufacturers can carry out an analysis of your oil.  Probably best way to determine if your oil needs replacing, if your using the correct oil and likely condition of bearings, gears and synchros etc. 

The analysis should include a comprehensive viscosity test where the degree of shearing of the polymer molecules is determined.  If the viscosity has reduced because of excessive shearing then definitely time to change oil and probably oil type.

[bonno]

Based on my research, the mineral based oil meeting SAE 80W90 would be my preference at a 1/3 of the cost of the synthetic product used for racing applications.
Specification  - Redline lightweight shockproof gear oil Synthetic ($120)
https://www.redlineoil.com/Content/files/tech/LTWT_SHOCKPROOF_PROD_INFO(1).pdf
Specification - OEM recommended gear oil SAE 80W/90 ($40)
PS Refer Product details and pdf spec.
https://www.valvoline.com/en-australia/our-products/transmission-and-driveline/Valvoline-HP-Gear-Oil-80W-90-with-LS-applications

[bazzbazz]

Castrol, Shell and probably a few other manufacturers can carry out an analysis of your oil.  Probably best way to determine if your oil needs replacing, if your using the correct oil and likely condition of bearings, gears and synchros etc. 

The analysis should include a comprehensive viscosity test where the degree of shearing of the polymer molecules is determined.  If the viscosity has reduced because of excessive shearing then definitely time to change oil and probably oil type.

Yes they are called SOAP samples (Spectrometric oil analysis programs), we carry them out on all RAAF aircraft. Ahh, just how much do you think getting one of these done costs?   

I think you'll find it to be somewhat cheaper to just change the oil. 

[bazzbazz]

Actually I stand corrected, obviously the SOAP done on civilian vehicles is not as comprehensive as for aviation and can be done for a bargain $39.00 by Nulon. But then, how many people here can really read and understand what a SOAP report is telling you.

If anyone is interested, just for shits & giggles, here's the link -

https://www.engineoiltest.com.au/product/oil-test-kit/

Don't know if it applies to gearboxes. 

[Colin Edwards]

Shell perform a reasonably comprehensive oil test and report for $60.  Gearbox is the Hewland LD200 transaxle fitted to a Spectrum Formula Ford.  Oil sample sent to Shell at the conclusion of every race meeting - 5 x times a year!   
Gear boxes are expensive.  Lubricant and its testing is comparatively nil cost!