I have a 1974 jaguar xke and would like to use synthetic oil in the transmission, final drive, and the engine. I have heard that red line products are among the best. If anyone knows what the best synthetic for each component is, please let me know along with the proper viscosity. I am also going to change the brakes over to silicone, and need info for doing that. Thanks, Jerry Nutt

Submitted by bonnettoboot@e… on Sun, 04/16/2006 - 18:48

I have no comment on synthetic oil, I have used it once but use regular single grade in everything else(unless the manufacturer says otherwise. As for silicon brake fluid, I have converted hundreds of cars over the past 20 years and continue to do so -mainly jags. Normally the conversion is done when a repair is being made to a part of the system but not necessarily, It is a simple operation to bleed out the system and refill it with Silicon, start the process at the farthest rear calliper from the Brake cylinders, bleed out slowly until 1 reservoir is just empty, now clean out that reservoir and change the cap and float. Refill with silicon and continue the bleeding until clean silicon is emitted. Now bleed out the other rear calliper. Go to the front callipers and go through the same process. It is usually worth replacing both cap/float assemblies as the aluminium shield is usually corroded. Jaguar affectionado and etc.

Submitted by ianc@uvic.ca on Sun, 04/16/2006 - 00:59

Edited on 2006-04-16 1:01:05

I don't think synthetic oil is a good idea for the Jag. The engine doesn't rev high enough to need it, and given the change periods and the capacity, it'll be pretty expensive. I've used synthetics in both engine and gearbox on other cars, and for older cars, I didn't see much improvement. But that's your pick. On the other hand, I urge you NOT to change to silicone brake fluid. DOT 3 and 4 fluids are glycol based, and are not mixable with silicone. Unless you are willing to strip the entire system down, and clean every part, simply draining the system of DOT 3/4 and adding silicone will be a disaster. And in the long run, silicone is not a better fluid. There is no reason at all to change, and every reason not to.
1969 E Type

Submitted by mfrank@westnet.com on Sat, 04/15/2006 - 23:56

I've been using Mobil 1 0w-40 in the crankcase, and it seems fine. I like it because the pressure builds very quickly after starting. Other than that, I see no advantage. Despite claims to the contrary, I've always found that synthetics tend to make any leakage worse. Use only in a tightly sealed motor.

I would recommend sticking with conventional lubricants in your differential. The diff has leather seals, which do not like synthetic lubricants. I recently picked up some Royal Purple for my transmission, can't comment on it yet.