So, I’m going to be getting the Jag (1978 XJ6) Taken in for a service and oil change. I have used AMSOIL for years in my personal vehicles and wanted to use it in the Jag. I wrote AMSOIL for advise and here is the response:
Joseph,
Thank you for your email.
The AMSOIL ZROD 10W-40 Synthetic Engine Oil (product code ZRD) is recommended to use in this Jaguar engine. The ZRD is perfect for classic vehicles.
We hope this is helpful.
So what are some thoughts on this? Also the service center where I am getting the service done said for me to use:
Engine and Transmission Flush
PRODUCT CODE : FLSHCN-EA
Prepares Engines and Transmissions For New Oil
Engineered for both gasoline and diesel engines and automatic transmissions. Helps improve operating efficiency, increase fuel economy and reduce emissions.
I use the cheapest 20W50 and in theory change it frequently. When I topped it up with 15W40 (Englands‘ cheapest) the pressure dropped noticeably, but not a concern.
You will not save much fuel, just waste a lot of money and potentially invite leaks.
The 4.2 has its share of problems (better change coolant every second year!), but oil is not really one of them. 10W40 is certainly lighter than Jaguar recommended, but would work, sure. I‘m against it. It’s like feeding your dog caviar. Flushes are also more trouble than good.
20W50 is the best.
David
Of course I have nothing against Amsoil and if you have your oil changed there… give it a try. Don’t allow the flush thing, though. It might dislodge crud, but consider where that will potentially end up!
I agree with David 10W40 IMO is a bit on the light side, however I did a test on a BMW engine once using Wynns engine flush, a back to back compression test.
Prior to the oil change we did the compression test, introduced the Wynns and aloud it to circulate for the recommended period, drained and refilled and re did the comp test. The figures came up about 5 psi from memory.
I can appreciate the possible damage to an engine if the oil changes have been irregular but if they have been carried out fairly consistently then the engine shouldn’t have too much crap sitting around.
You never said it was your first Jag, but welcome. The kindest way to treat your Jag is to drive it. They need regulat exercise and because they all have large engines they take a while to warm up their bones properly after the water gauge says the coolant has reached temp. Oh, and NEVER use plain water, always correct coolant.
Be aware that the special Jaguar ride comes from the use of rubber bushes etc. that over high mileages and harsh heat or ozone eventually wear out. This isn’t a ‘fault’ it’s just a fact of life. Using factory spec parts is the way to go. Hard rubber cheap copy parts often aren’t as good.
Drive it often, don’t baby it, change the oil, go over the grease points from time to time. Get it warm and don’t do many short drives. These cars love long distance.
I will always recommend the poly bushes for the steering rack and rubber for the rest. The only parts that are really safety relevant ar the mounts of the rear suspension when on a lift and the steering rack bushes give vague steering and play when gone.
Nothing about the mechanicals is expensive or complicated. It should not cost you anything extra or need a special shop for the normal jobs. As long as you keep an eye on the gauges and don’t hear any unusual noises, almost nothing can go wrong. The engines have been designed for what was available in the 50’s and with heavier oil you will have a better experience.
