I have a 2015 V6S which was at the dealership for new belts and tensioners and some ac work. While there, I asked them to also change the differential fluid as the car has just under 45,000 miles. Picked the car up today and when I just checked the invoice it says: Installed BG 75164 Ultraguard 7590 syn. Is this the correct spec for the differential in this car? Any idea if I need to be concerned that it is not the specified Castrol fluid?

Thanks!

 

I doubt that you need to worry at all. BG products are very highly regarded and in fact my dealership uses them at every service (but the engine oil used is always the Castrol Edge Professional). As long as the fluid was for a limited slip differential and in the correct viscosity you’ll have no issues.

 

Thanks for the reassurance!

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Agreed, that fluid will be perfectly OK and at least as good as the JLR recommended Castrol BOT 720 and it is for limited slip diffs, see here: https://www.bgprod.com/catalog/drive...ear-lubricant/
Note that 75164 is the part number for the 64 oz / 1.8 litre bottle.

 

Good to hear, thank you. The dealership has been incredibly helpful and I was assuming they know what they are doing. I have dealership PTSD from prior brands so it is quite a change.

 

I took my 2917 S in for fluid changes. Only 15,000 miles, but 7 years. My mechanic, trusted and well respected guy with many high end car customers, put Liquid Moly in the diff along with a bottle of Redline limited slip diff additive. Good quality stuff. When I got the car back I thought I started hearing some groaning from the rear during tight, low speed turns. Got worse over 300 miles until I was sure I was hearing it. Took the car back, he replaced it with the Jag OEM BOT 720. He told me that he found some separation in the OEM fluid, a layer of something heavier separated out at the bottom of the bottle. Something he had not seen with other fluids. He shook it up well and put it in the diff.

Just drove the car and the groaning is totally gone, silent and feels perfect doing slow figure eights and then on the freeway home. Problem, solved. Our theory is that the heavier stuff at the bottom of the bottle is the Jag secret sauce.

 

Lake Speed Jr "The Motor Oil Geek" ALWAYS advises that fluids should be shaken (not stirred ) before filling.