The owner's manual for my XKR indicates a synthetic oil to be changed every 10000 miles. My dealer is not using the synthetic oil and recommends a 5000 change. Does anyone have an opinion on this?

 

In my personal opinion i would recommend you ask your dealer to replace your oil with synthetic. I am no ASE certified mechanic but synthetic oil is a all around better oil in performance and durability. I personally use Mobile 1 Synthetic and change it between 5 and 7 thousands miles. Some say you can go 10,000 mile before changing synthetic oil but i rather be on the safe side. Its cheaps insurace and cost only a couple dollars more than conventional

 

just a little note ,but if you are going to use fully synthetic oil you can't go back to using a semi synthetic oil

jaguar don't recommended fully synthetic only semi synthetic oil for the ajv8s engine for some reason.

 

As far as frequency, there is no such thing as changing oil too much regardless of what you are using.

 

I've never heard that there's an issue going from synthetic to normal and back. Do you have a source? I'd love to read it.

Here's what Popular Mechanics has to say about the issue:

http://www.popularmechanics.com/cars...oducts/4213451

 

The XKR converts a lot of chemical energy in the fuel to BTUs with the blower, it should have synthetic in it to slow down temp breakdown. Synthetics are more stable than standard oil in high temps, why not protect this investment? I use Mobil1 synthetic oil and change it between 5000 and 7500 miles. If you can look in the oil fill hole and see any color other than silver bare metal, your engine is sludgy, not a good thing with things like VVT and such.
I am no petro chemist, but my reading over the last 30 years tells me that switching back and forth between standard oil and synthetic has no effect on the motor. Synthetic is not slicker, just longer lasting in the good lubrication ad cleaning range.
Over the years, I always get a chuckle about the hesitation to use and change synthetics frequently due to high cost..usually by enthusiasts that own high end performance cars!!!!Go figure!

 

Not this again

 

I know, from personal experience, the life of non-synthetic motor oil. When I was young and stupid I drove a brand new car 18,000 miles without ever changing the oil. One day I started the engine, drove about a mile, and then I heard this horrific screech and the engine stopped dead. The connecting rods had welded to the crank. I've used synthetic oil ever since. I get my oil changed on schedule now, but since synthetic is supposed to go 15,000 miles between changes, I figure if I ever exceed the recommendations I'm not going to do any damage to the engine. The cost difference between regular and synthetic is only a few dollars per quart. Even in an XK8 that takes 8 quarts, the cost difference is less than $30. Using synthetic every time isn't going to break me.

 

If your owner's manual specifies synthetic oil, then go with it. Don't try to second guess or out-engineer.

 

On a related question, what weight oil do you guys use. I just had the car serviced at the dealer and the workorder indicates Castrol 10w30. I somehow thought 5w30 was the oil of choice but perhaps 10w30 is more suitable for southern California. Also, I thought Castrol made both synthetic and "natural" so how do I know which they used?

Thanks,

Doug

 

Doug, I use 5W30 synthetic. I would guess if it doesn't say on your receipt that they used synthetic then they used conventional. I will have to check the manual, but there is a different oil recommendation for sustained heat and I don't think it was 10W30.

 

Dear Sir
Thank you for contacting Jaguar Cars
Further to your enquiry.
Having been advised by our Technical Team the reasons for not using fully synthetic oil is that years ago fully synthetic oil would cause damage to the oil seals. This is no longer the case, mixing semi and fully synthetic oil will not cause any damage.

We do not recommend Semi or Fully. Both are equally as good as each other.

Thank you once again for contacting Jaguar Cars.
Yours sincerely
S**** J*****
Jaguar Information

must apologise for oil information.just showing my age

 

*** proper weight of oil is perfectly allowed discussion topics here; the debate over dino vs synthetic is not

Proceed with care.

 

although i'm new to this forum .when you refer to dino do you mean mineral oil.

 

dino = dinosaur (the conventional oil)

 

If you do a lot of short, slow speed journeys, change at 5000 miles. You won't really need synthetic if you change this frequently, the main thing is to change both oil and filter at "appropriate" intervals. Oil is cheap, engines are expensive. (although full synthetic seems a bit eye-wateringly expensive)

 

what i don;t understand is ,why jaguar didn't put in fully synthetic oil in to start with ,it's been around for long enough now,

do they recommended fully synthetic oil for any of there cars?

 

This has been thrashed and bashed a hundred times before- synthetics have no real-world benefits unless the extended change interval is taken advantage of. Exception to this rule are the very, very few engine types that actually require them as specified by the OEM. S-types and most other Jags do not require them.

 

I disagree. What happens if you're on a deserted highway and your radiator hose blows? With synthetic oil you can limp to a populated area because synthetic oil can handle much higher temps than regular oil while still protecting the engine. Another forum member right now thinks he may be having problems with an engine that's getting too hot. If he's using regular oil he may be doing damage. With synthetic he's probably fine. Turbochargers spin at 60,000 RPMs or more and have to endure enormous heat from the hot exhaust gases. I wouldn't dream of using anything but synthetic in a turbocharged engine. I put synthetic in my daughter's car because I know for a fact she's going to be lackadaisical about oil changes. Synthetic may save her engine. There are lots of other reasons to use synthetic. It's better oil.

 

How about more horsepower and torque? Is that a real-world benefit? Read down near the bottom of the article where they tested the conventional oil against the synthetic.

http://www.carcraft.com/techarticles...oil/index.html