Oil consumption - limits

Post by **Stubee** » Fri Mar 20, 2009 10:48 pm

Just reading all these various topics over the past few months about oil consumption. I've not seen anything that gives a sort of limit. What would be considered normal for a 1098cc engine, say new and part worn? The 500mile to the pint has been suggested for new which would equate to about 1000 miles from max to min on the dipstick. Obviously driving style would make a difference. I'd like to know what to expect when my engine is sorted.

Post by **bmcecosse** » Fri Mar 20, 2009 11:53 pm

Yes - that would be a fair consumption for an A series - once properly bedded-in. The oil level should never be allowed to fall to the 'Min' mark on the stick. At that level it can fall away from the pick-up on cornering - and starve the bearings of oil - which ruins them almost instantly!
Cooper S engines used to do ~ 50 miles per pint - even when fairly new!! But that's a pretty smokey engine if it's burning that amount of oil. BMC fobbed off owners who complained by saying that was 'normal' !

Post by **rayofleamington** » Sat Mar 21, 2009 5:43 pm

I don't think there is a 'normal'. Some of my 1098's have usedm hardly any oil on long journeys but been very worn. Others have used more oil but been less worn.
I guess the condition of the oil rings and valve guides as well as the amount of leaking is not always connected to how worn the bores and bearings are.

Post by **bmcecosse** » Sat Mar 21, 2009 7:16 pm

If there is good crankcase 'suction' through breathers - that helps oil consumption considerably!

Post by **MikeNash** » Sat Mar 21, 2009 9:53 pm

Hi Stubee!
If it helps, my 1098 had a re-conditioned engine (Gold Seal) in about 1966 and now after about 100K miles does 200-250 miles to the pint when driven briskly (60-70mph true) on long journeys. So on a 600+ mile trip to Newcastle I carry a can of Adsa's fines (now £6 a gallon!). I get a film of dirty oil on the back windows of my Trav - but the underside is rust free! MikeN.

Post by **rayofleamington** » Sun Mar 22, 2009 1:25 pm

A film of oil on the back windows of a trav is usually a leak* rather than the exhaust.

* can be engine or gearbox leak

Post by **bmcecosse** » Sun Mar 22, 2009 1:26 pm

Or lots of fume blown out the breather!

Post by **MikeNash** » Sun Mar 22, 2009 2:22 pm

Rays right!
Definitely oil leak in this case, mostly from the rear crankshaft "seal" and out of the hole at the bottom of the clutch housing - hence the rustfreeness of the underside. My overall point for Stubee is that old high mileage engines can use (or leak) oil but still go well, and also to give him some figures he asked for.
If you've good compression you'll have good performance (given of course reasonable carburation and sparks). You just change to cheap oil!
MikeN.

Post by **bmcecosse** » Sun Mar 22, 2009 3:56 pm

Well - that crankcase seal leakage is caused by presssure in the crankcase - so good breather connection to the carb should help that!

Post by **MikeNash** » Sun Mar 22, 2009 8:02 pm

I've got that! One day I'll pull it to pieces and sort it, but it just keeps going to well! The real killer will probably br the oil pressure - down to 42 psi when the oil's really hot ie 200F and +.
Re the dipstick, Stubee, mine is 13/16 inch between MAX and MIN and is exactly the level change brought about by two pints of oil. And in the '40s throuogh to the 60's (at least) you could buy oil in quart cans, or might have a special quart "jug" for measuring from a 5 gallon drum. But perhaps you're old enough to remember that! MikeN.