by Glyn Ruck » Tue May 04, 2021 2:31 pm
cass3958 wrote: ↑Tue May 04, 2021 10:35 am
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.
[quote=cass3958 post_id=6962 time=1620124537 user_id=54]
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.
[/quote]
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.