Oil & spec for 3.8 with Powr-lok limited slip differential

[jonesdl]

Last oil topic at present the correct grade & specification for a 3.8 with limited slip differential, again I would use a Castrol product by choice.
Regards
Dave J.,

[Glyn Ruck]

Any API GL5 LS SAE 90 product from a reputable supplier. Mineral or synthetic OK.

Example:

https://www.amazon.co.uk/Castrol-Axle-L ... way&sr=8-1

71GPxhaFxxL._SL1263_.jpg (157.83 KiB) Viewed 1999 times

[jonesdl]

Many thanks Glyn, I have never seen that grade before so I will have look around to find all the S Type oils now I know what to look for regarding the correct specifications and grade.
We are so fortunate to have an oil expert on the forum.
Regards
Dave J.

[RollyTG]

Glyn - the axle oil you posted doesn't seem to be available. Would this one - Castrol Syntrax Limited 75W-90 - on amazon at
https://www.amazon.com/Castrol-06674-6P ... 87SZPRF0FC - be an equivalent?

[Glyn Ruck]

That would be fine but for nice quiet rear axles on our cars I prefer going a little heavier. I'm running 85W-140LS in my car. Dead quiet axle. 75W -140 would also be perfect. Axles are forgiving things as long as viscosity is adequate.

Any of these are suitable.

Castrol LS 75W-140.JPG (149.54 KiB) Viewed 1659 times

Castrol Axle 85W-140 LS.pdf

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[RollyTG]

Thanks for that. I have only just begun to test drive my car and it may be that my diff will be an issue. It doesn't seem to be making any terrible noise though.

[Glyn Ruck]

If you have put GL5 75W-90 LS in the diff & its quiet from accelerating to trailing throttle at all speeds then all is well. Jaguar did not even demand limited slip oils but having the friction modifiers present will ensure smooth operation in high torque turns.

[cass3958]

Out of interest what would you recommend for a standard Non LSD rear diff Glyn. I need to change the oil in mine so would like to know which is the correct oil to use.

[Glyn Ruck]

Out of interest what would you recommend for a standard Non LSD rear diff Glyn. I need to change the oil in mine so would like to know which is the correct oil to use.

Rob GL5 SAE 90 or anything from 75W-90 to 85W-140 non limited slip. There is no point in paying for friction modifiers if you have no clutch plates to worry about juddering under torque. This is not a particularly critical lubrication area as long as the product is min GL5 & minimum an SAE 90 hot. Don't be scared to go a little heavier if it helps with whines. I rebuilt my diff to the book. Accurate tooth meshing & proper pinion bearing preload. I did not replace the gear set & it is dead silent.

GL5 additive depletion rate is slow & you service your car so going synthetic is likely also a waste of money. Nice but not necessary if you are going to change it every 20K miles or whatever. Sulfur phosphorus additives are sacrificial so deplete slowly but many cars will do 100K miles or more without a diff oil change. A magnetic drain plug is sensible if available as it will trap any wear debris from the gear set & keep it out of modern close tolerance pinion bearings.