Oil consumption on a XJR 1998 with 75k??
Oil consumption on a XJR 1998 with 75k??
Author
Discussion

fast cars

Original Poster:

269 posts

231 months

Wednesday 21st November 2012
quotequote all
This car has full history, no smoke from exhaust but on a recent run used 3 liters of oil over 560 miles, is this normal? no leaks anywhere and no smoke - where's it all going??

LoudV8

930 posts

289 months

Wednesday 21st November 2012
quotequote all
No not at all normal.

There are only 2 things that can be happening - it's leaking out or being burnt.

Jaguar steve

9,232 posts

236 months

Wednesday 21st November 2012
quotequote all
Some oil consumption is normal on higher mileage V8s. Thinner fuel economy oils such as 5W/30 may also burn off at higher rates.

Check oil with the engine cold and the car on level ground - ideally once a week if you think you have a consumption problem. Whatever you do don't let the oil level go below the minimum mark on the dipstick. You run the risk of oil starvation on hard cornering if you do.

fast cars

Original Poster:

269 posts

231 months

Wednesday 21st November 2012
quotequote all
thanks Steve and company for the reply, how much should one of these cars use - if known?

Jaguar steve

9,232 posts

236 months

Wednesday 21st November 2012
quotequote all
My old 100k V8 used a couple of litres every 7-8 k or so between oil changes. My curent 36k V8 seems about the same.
Both run on fully synthetic 5W/40

At very high rpm or heavy load any hard driven engine will always use more oil than a lightly loaded one as the oil scraper rings on the pistons flex slightly and loose efficency.

Another cause of high oil consumption on the V8 is a blocked breather pipe leading to excess crank case pressurisation - there's a calibrated 2.5 mm hole in the stub of the cam cover on the left bank part load breather pipe. Worth checking this is clear and none of the other breather pipes are blocked. With the engine hot and idling turn and lift the oil filler cap slightly. If there's any significant pressure or a rush of oily fumes out of the engine then this may be the problem.

fast cars

Original Poster:

269 posts

231 months

Wednesday 21st November 2012
quotequote all
Steve as always a big thanks for your professional advice, will check this breather also what oil grade would you recommend for an older engine?

Cheers
Danny

Jaguar steve

9,232 posts

236 months

Thursday 22nd November 2012
quotequote all
I'd stick with a 5W/40. There are marginal fuel consumption benefits from going thinner which Jaguar permit, but IMO quality of lube oil and changing it regurlarly is more important than the differences in viscosity between say a 0W/30 and a 5W/40.

I've always ben happy to pay more for a fully synthetic oil - providing you make sure that's really what's in the can and not just written on the label.

Synthetic has much greater heat dissapation properties and unlike mineral oils stays in viscosity grade throughought it's service life. It also has a much better lubrication effect then mineral oil which will save fuel and reduce wear rates on critical components like timing chains. All other things being equal it should help to control oil consumption as well but no oil on the planet is ever going to mend a tired engine.

If you're going to check the part throttle breather the safest way to clear the calibrated hole inside the pipe mounting stub is to carefully use a 2.5mm drill bit by hand.


fast cars

Original Poster:

269 posts

231 months

Thursday 22nd November 2012
quotequote all
many thanks again Steve, i will give this a go...