Please any Jag techs or anyone with sound knowledge can help me answer this debatable question about using Rear Differential Oils that contains limited slip additives or NOT.

My first choice is choosing Amsoil 75W 140 synthetic which is Ford/Jaguar compatible M2C192A, but it DOES contain limited slip additives. http://bestsyntheticoil.com/dealers/...-75w-140.shtml or If I should stick with STA-Lub Syn-Go 75W-140 (http://www.performanceonline.com/STA...75W-140-SL2496) as an alternate from OEM JAG differential oil that does NOT contain any limited slip additives. My main concern is, if I go with the Amsoil 75w 140 that has the limited slip additive will it cause any problems?, Few days back I went to the Jag dealer and they brought out a bottle of "Castrol oil called SAF XJ 75W140. The bottle had huge letters "made for BMW differentials" on it. The crooks wanted 91 dollars for a litre! The BMW dealer was half that price. I did not buy it. This stuff is a synthetic 75w140 gear oil WITH limited slip additives."
As you can see now, the Jag dealers are using differential oils with Limited Slip Additives by Castrol, so this looks like a debatable issue to use or not to use differential oils with or with out limited slip additives for the Jags.

If anyone can please give some insights and suggestions to this issue, Others and myself who plan on changing their Rear Differential oils can benefit from this.

Thanks.

 

For open diffs the recommendation from Castrol/BMW is the use Castrol SAF XO, there is no doubt so that should be the preffered choice imho. However it seems the Castrol SAF XF (different oil with clutch plate LSD additives) could just as well be used. I think the XF is the better choice for the stype as it is Gl-5 and is of the same weight as the standard oil.

 

Ask them why in the hell they use a lubricant with limited slip additivies for a non limted slip differential? If it doesn't hurt the diff then I suppose it saves them from having to stock two types?

I have no idea about the quality of Sta-Lube. I remember when it first came on the market it was always the bargin brand where ever it was sold so I've never used it.
I've used Swepco, Mobile One, Redline, Castrol and Valvoline.

Bob S.

 

The Amsoil 75W 140 meets the Ford/Jag requirement M2C192A, plus it has the LSD additive and provides GL-5. Please take a look at the link with its Specs: http://bestsyntheticoil.com/dealers/...-75w-140.shtml .Considering all that Amsoil should be just as good as the Castrol thats being used by the dealers. Plus at $12 a quart of Amsoil is a lot cheaper than paying $91 a quart for Castrol at the Jag dealer

 

UPdate: Bmw dealerships are selling the Castrol synthetic 75w 140 SAF XJ(for Jaguars also), 1L $18, $9 half a liter. YOu bring your own container they fill it up for you , but I'm still going with Amsoil 75w 140 which is the same weight and same shiat in it with the LSD additive for $12 a Liter

 

[quote=Staatsof;263165]Ask them why in the hell they use a lubricant with limited slip additivies for a non limted slip differential? If it doesn't hurt the diff then I suppose it saves them from having to stock two types?

That's exactly it. Whys tock 2 types when one will do. The additive will do no harm if not required. Local Jaguar and Volvo dealers both stock just
the Castrol oil.

 

I'll write it again...Limited slip friction modifier does nuttin to harm the S-Type's open-differential. The only thing the friction modifier does is help cut friction between the individual clutch plates in a limited slip differential. The entire assembly of an S's diff. is the same as a LSD except no clutches.

 

it might help the gears slide easier= faster! lol

 

+1

 

Won't hurt, won't help in a standard (non-limited slip) differential.
Either way, the Motorcraft, Amsoil or Castrol XAF in 75W-140 weight will work fine. I used the Motorcraft 75W-140 in my S-Type and will use it in the XJR (once I drain the non-synthetic that I am running for the first 3000 miles in the rebuild differential - failed not due to fluid but a bad repair - shop didn't stake the pinion nut in place...)