Hi All,
I´m wondering what oil is best fot the syncro´s to work fast...

I have installed a 6speed gearbox with 3kmiles on it and when the car have been through the gears at full speed a few times the syncro´s will begin to crunch.....is the oil mayby getting to hot??
The oil that´s in the gearbox now is castrol Syntrax 75-90w...Is there a better oil than that(i´m thinking about the syncro´s )

Thanks,
Skassa

 

There certainly should not be anything wrong with the oil Skassa. I wonder if the gearbox is running hotter than it should. Maybe it is just still running in though.

Les

 

I have been advised to use Redline Shockproof (light weight for my needs) as the best oil for the synchros, not sure though if this applies to your case.
JIM

 

I've had problems with 4th gear synchro for 2 years and been recommended various things including changing the oil by 'somebody in the know' to Redline 75W90 NS at a cost of over £50, well it will have to come out again, because it made it worse! Does anyone really know what is wrong with the synchro on these boxes, and can any oil fix it ? Or is it really a gearbox rebuild at 28,000 miles, and would this fix it anyway ?

 

if you run any decent quality fully synthetic oil (75w90) then you should have no problems, however it is possible to beat the synchro if you are really fast and aggressive whilst changing gear...........this may be the problem you have??
have you checked for swarf on the drain plug??
alyn - asperformance.com

 

I know that some manufacturers ( honda methinks) actualy reccomend using ATF in gear boxes... volvo definatly do..

apparantly it handles shearfore and loads very well

Mart

 

Actually the fully synth is possibly the problem, its too slippy and the synchro's could not be biting causing the crunch. Try a semi synthetic gear oil (Subaru uses Shell) and see if that makes any difference. You will need to change it twice to get rid of the fully sync at say 500 mile intervals.

cheers

bob

 

Thanks,
I´m using Castrol Syntrax,and that is semi synthetic,but perhaps i need to change it again....

I think Subaru would also use semi synthetic from the start,and my gearbox was only 1700miles old when i got it..

Thanks,
Skassa

 

Stockar,
Yes I am " very fast and agressive " ha ha ! but that isn't the problem, it doesn't matter how careful and slow you change, it still crunches.. unless you match the revs perfectly so that the synchos not actually doing anything! the Redline oil made it worse, but apparently Subaru have a 'special oil' (magic?) that may fix it, Part No K0324AA093 anyone heard of this?

 

BTTT

Anybody know anything about this oil ?? I have the same issue with 4th and i run redline !!!! DO you think it's worth changing to something else if so what ??

 

Hi,

Shell developed special gear oil in cooperation with Subaru which is called Shell SL. It's a bit on expensive side (20EUR/litre) but deffinetly worth it. By the way it is 80W-90.

Reg.

Kristijan

 

run "fully" synth in all of our own road & competition cars (as well as an awful lot of customers) and never had any issues or complaints (say it quietly, no doubt there'll be a rush now?!! LOL)
the problem is the 'soft' box at the end of the day, they should take a leaf out of Mitsubishi's book!!!
alyn - asperformance.com

 

My preference:
Redline shockproof lightweight
Neo
Castrol syn.

Chris

 

try looking on the oil thread on 22b, there are some useful contributions from people who really know their stuff!

It does refer to engine oil, but gearbox oil comes up at the end.