So, after doing a fresh oil change about 2500 miles ago, I was doing some "harder driving" in sport mode, and noticed a lot of oil use, about 2.5 qts low.

I am curious if this has anything to do with the sport mode or if it's just worn rings?

I am currently running LiquiMoly synthetic 5w-40.

When I was running Mobil1 Full Synthetic 10w-40 it seemed fine.
Would it be advisable to run a heavier oil? 15w40?

Anyone else have any issues like this?

 

Mine uses no oil between changes on the following:

Shell Rotella 15W40 dino
Shell Rotella 0W40 synthetic
Castrol 5W50 synthetic
Castrol 0W40 European synthetic

under similar climate conditions.

Have you checked your throttle body for excessive oil accumulation?

That might indicate missing steel mesh in the valve covers at
the breathers which in turn means higher oil consumption.

Some accumulation is normal, so "excessive" is in the eye of the
beholder. But if it coats the inside of your intake tube ... that is
excessive. If your air filter or MAF are soaked, that too is excessive.

 

Can only say that going back from a 15W50 to a 10W40 did not lead to oil uses for my car.
2.5 qts on 2500 miles should surely leave traces.

 

None of mine use any oil -- M1 5W-30. How many miles on the engine?

 

As far as burning oil goes, the latter (hot) viscosity is the more important number. 0w40 and 10w40, for example, should behave more or less the same when hot, which is the main influence on oil burning, after engine wear.

Any of the oils the OP has used should be fine. In fact, a 5w40, vs. a 15w40, would be expected to provide better lubrication when cold. If you want to really reduce oil burning, you need to raise the second number - ie, a 5w50. It shouldn't be necessary, though. A 5w40 is already thicker than the Jags shipped with (5w30, I think).

Another "however" : oil viscosities are rounded off. So two oils rated, for example, 5w40 could in fact be 5w44 and 5w38, which is quite a difference - 15%. The true guide to their behaviours are the cold and hot viscosities in Cst, usually available in the specifications.

I would be checking the breather system. Have you checked the part load and full load breathers for blockages?

 

In response to Plums, this started to become an issue right around the time I changed the oil last, I also cleaned the TB, at the time I did not see any traces of oil in the intake tube. As far as the part load breather, I cannot safely remove it without potential damage. I did however clean it out when I had to replace it before.

The engine is at about 127k. I've noticed that in the past it used some oil, which it did have a minor oil leak that has since been repaired, and I have not seen any oil on the driveway. I look at the exhaust tips and they are BLACK. I've had several people comment on the plums of smoke that come out when it's in sport mode and I give it the beans. It seems to be worse in the sport mode. Not sure if that's related to anything. It'd surprise me if the viscosity of the oil is that far off, especially for the price (people put it above Amsoil). Seemed to do pretty well with the Mobil 1 10w-40 and a bit of Lucas heavy duty oil stabilizer. But I cannot for the life of me find the 10w-40 anywhere.

But it's becoming a serious problem.

 

The thing is, a quart per 1,000 miles is not actually that bad. That is the specification for a new Audi, believe it or not. Your engine certainly has some wear, but could go on for years.

My Cortina reached a pint every 100 miles, before suffering from compression failure - now that was smokey.

I'd think about putting some 5w50 in there.

 

Outside of the breather system pushing oil in a mist out of the crankcase and barring any signs of actual leaks oil film being washed off the bores due to worn rings or worn valve seals would be the main places I'd suspect. Heavy oil use should show up on the plugs so that might be a good place to start. You can check compression while they're out and see if there's a change when you put a small amount in thru the plug hole after your initial readings. I wouldn't call 2.5 qt/2500 mi terrible but I don't think it's expected on these engines. My 99 XJR doesn't really use any between 5k mi changes. I use 5W30 dino in mine and she's got 85k on the clock...

 

To put it another way, the Cortina's oil consumption was 1.25 quarts per cylinder per 1,000 miles! Yours is 0.1125 quarts per cylinder per 1,000 miles.

You mentioned you cleaned the part load breather. What about the full load one? IIRC, the part load is on the left bank, the full load on the right (same as the air filter).

 

Remove the large air intake pipe and inspect that for oil, also check the air filter. If the engine suffers from blowby due to worn rings or cylinder damage I would expect oil in the intake pipe and maybe even on the filter. It's probably a nikasil engine and motorcarman mentioned the possibility of damaging the liners by overheating if I remember correctly.

If all that is clean it almost has to be leaking past the valves.

 

RJ237, there is a slight kink in the full load breather, but no oil in the intake tube. It is a Nikasil engine, and to my knowledge has never been overheated. Plugs are fairly new so I will pull them and see what they look like and do a compression test.

How difficult/expensive is it to replace valves/seals on these engines?

 

If the full load breather is blocked, you would expect no oil in the air intake anyway.

 

Blocking the full load breather would be difficult considering it's size.

 

My XJ8 loses oil every now and then even though there is no leaks. Not to much oil, just a little less than a quart/liter. but there is some bubbles created on the dipstick when checking the oil.