Oil consumption improving - why?

millsy

4x4 Earth Contributer
The old MQ seems to be coming good on the oil consumption issue.

I drove it really hard on the weekend, out to the Morgan quarry, which was about 360 km round trip, at about 95 km/hr. Thats pretty quick for the little 2.8 litre motor on LPG ( at least compared to the 80 km/hr I normally do! ). Did a similar speed for the last 300 - 400 km coming home from Victoria a week ago.

Both times the oil consumption seemed to be much better than before.

I have two theories and am looking for any feedback on them or any other theories. I know there are a few mechanics on the forum. Maybe they can comment please?

Is it that the rings have lost their spring. By driving fast and therefore causing greater pressures in the cylinders, the rings are getting 'blown' out against the cylinder walls, and so sealing them better against letting the oil slip past them on the power stroke.

The other thought is based on the difference in the sooty sludge that hits the driveway whenever I start up the motor in the mornings and give it a few revs to get the oil pump circulating a bit of oil before driving off. When I first got the car there were big blobs of carbon mixed in with the condensed water from the cold motor/muffler. Now, after about 16000 km, there is just a hint of carbon material mixed in with the water on the concrete. Certainly no large lumps, just a fine powdery residue.

So maybe the thicker oil I am using, and the few fast trips just lately, has cleaned out a carbon build up behind the compression rings, and maybe the oil control ring.

Is anything I said possibly on the right line?
 

Grumpy

Moderator
Just maybe a good burst has helped your car get a new lease on life, the wife only putts around town on short runs all the time and when I drive it I usually give it a bit of a go, she reconds I've done something to it every time cos it drives different, Beats me, I'm no mechanic. CHEERS
 

jessie928

New Member
its called an itallian tuneup.
a good thrashing is good for the engine, and it will wlways run better after a long hard drive
your engine was probably full of carbon deposits

Jes
 

millsy

4x4 Earth Contributer
Thanks fellas. Look forward to getting out there and keeping up with those modern cars more often! Certainly keeps it safer for every one concerned since less people trying to overtake - but then again when they do they use up a lot more road!
Had a semi overtake me when I was already doing 95, and he crawled past me at about 98 !! Before he even got level with my door there was a crest in the road just ahead and I had to head off to the left in case a car was coming over the hill ( which there was, just after the semi pulled back over). This was in the Barossa Valley section of the Sturt Highway - a narrow section notorious for head-ons! And 2km further on an overtaking lane, but he couldn't wait! I don't envy them - tired, stressed and just want to get home!

A mate told me about a Nulon product. Some sort of de-coking stuff that you add to your oil. Will have to have look at it and decide whether to use it or not. He says he uses it regularly and finds it quite good.
 
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Grumpy

Moderator
Hey millsy the old girl just might like going along with the other cars, does it affect your fuel consumption much. CHEERS
 

millsy

4x4 Earth Contributer
Yeah! But my mate had the opposite joke. When we stopped for a chicko and Farmers Union at the BP at Blanchtown, after about 200km, I checked the oil and it was just over the full mark! He reckons it must be MAKING oil !! I wish ! At $140 a barrel I'd be on to a good thing! Probably just a slight slope where I parked the car.

Anyway Lowlux, the missus has been driving my VR for six months. Last week the VR had a flat battery so I registered her VH for her to use while I went for my holiday drive, thinking that I was going to lay up the Patrol when I got back anyway. Now she says she does not want to drive her lovely VH - she prefers the VR. So that means if I de-register the Patrol, guess who gets the VH ! Mmmmm.

Decisions, decisions. One has to have a rest, can't afford to have three cars registered and insured! The Patrol gets 7 to 8 km/litre around town, the VH only 5 to 6. The Patrol is a lot more fun to drive, but city driving will probably not do it much good. Tricky one! ( All cars on LPG ). The VH looks and drives like a new car, all done up by previous owner - lovely metallic blue duco. The sort of places I go would probably just wreck it. I think I better keep the truck going! Yeah!!
 
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millsy

4x4 Earth Contributer
Hey millsy the old girl just might like going along with the other cars, does it affect your fuel consumption much. CHEERS
I think it did actually. But am not sure by how much. Only managed about 6 km/litre on Sunday instead of the usual 7 . ( Used to get 8 with the thinner oil! ) But we spent an hour or so crawling around the quarry in 1st and 2nd gear so will have to wait for a steady cruise to find out.
 

croozza

Active Member
The old MQ seems to be coming good on the oil consumption issue.

I drove it really hard on the weekend, out to the Morgan quarry, which was about 360 km round trip, at about 95 km/hr. Thats pretty quick for the little 2.8 litre motor on LPG ( at least compared to the 80 km/hr I normally do! ). Did a similar speed for the last 300 - 400 km coming home from Victoria a week ago.

Both times the oil consumption seemed to be much better than before.

I have two theories and am looking for any feedback on them or any other theories. I know there are a few mechanics on the forum. Maybe they can comment please?

Is it that the rings have lost their spring. By driving fast and therefore causing greater pressures in the cylinders, the rings are getting 'blown' out against the cylinder walls, and so sealing them better against letting the oil slip past them on the power stroke.

The other thought is based on the difference in the sooty sludge that hits the driveway whenever I start up the motor in the mornings and give it a few revs to get the oil pump circulating a bit of oil before driving off. When I first got the car there were big blobs of carbon mixed in with the condensed water from the cold motor/muffler. Now, after about 16000 km, there is just a hint of carbon material mixed in with the water on the concrete. Certainly no large lumps, just a fine powdery residue.

So maybe the thicker oil I am using, and the few fast trips just lately, has cleaned out a carbon build up behind the compression rings, and maybe the oil control ring.

Is anything I said possibly on the right line?
Fuel is getting into your oil and topping it up, it happens to all vehicles even new ones. In older vehicles check your timing and fuel system over, Unburnt fuel is draining into your oil and diluting it, so your oil is loosing its lubericating factors, I would drain the oil and start again to avoid engine damage.
 

millsy

4x4 Earth Contributer
Thanks croozza, but I am using LPG! I don't think that LPG is going to get into the oil, being a gas on the engine side of the converter. I do send a little petrol through the motor every now and then, just to keep the carby gaskets soft. But not very much, just two or three kms every 500 km or so, and the occasional 'soak' over night in the drive-way. The petrol pump is an electric pump not attached to the motor. I think one way petrol can get into the oil is with the mechanical type fuel pumps that run off a lobe on the cam shaft. I believe the diaphram can split, or become punctured, and so the petrol seeps through into the sump.

And I am certainly changing the oil very often. I started giving it a change every 2000 km to clean out the muck accumulated from the previous owner, and gradually have extended this out to about 4000 km. In the beginning the oil consumption was so great that it would use 100 ml after just doing a short 60km test drive! ( But I was using 20/50 ) Now it seems to go for well over 1000km per litre ( 100 ml per 100km and more ), but this being on the thicker oil ( 30/70 ). Over the 20000km since I bought the car the oil is staying cleaner for longer and longer, especially since I started using the 30/70 thick Penrite oil for old motors. Although I am a bit miffed at having to do this in a motor that has only done 246000km!

The car does not like short local trips ( less than 2km to work and to the shops ), and does not like longer trips driving through the traffic lights. This is where it spits a cloud of blue smoke if it has to idle for more than 30 seconds or so before the lights go green. This is where the oil consumption goes up. But on the open road a litre of 30/70 oil goes a 'long way' - 1200 to 1500 km! Wow!

So now that the initial thrill of playing with the new toy has worn off, and until I feel I have safely got my $2500 worth of trecks out of it, I will just register it for my holiday trips 'up bush', and then take it off the road and get the refund back on the unused rego. Just hope the 'coppers' are not sitting behind me one day as I take off from the lights and get a lung full. Then it will be 'over the pits' at the government checking station and a list of repairs a mile long! I have been turning the motor off if I just miss the lights to save the smoke problem, but this is getting a little tiring and is just going to wear out the starter motor and the ring gear, and another reason for just saving the old girl for the bush until I fix it.
 
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