1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

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Husky_Dog
Learner Driver
Posts: 79
Joined: Mon Oct 24, 2005 1:43 pm
Location: Norwich, UK

1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

Postby Husky_Dog » Wed Feb 04, 2009 12:34 pm

I’m hoping that someone on this forum might be able to help me with a concern I have with my 55 plate Megane Scenic 1.9 DCI which has done 56,000 miles… I have had the car from new.

The old girl has started to consume oil at the rate of about 250 ml per 5000 miles.

There is no oil leaking from the engine, so I am assuming that the oil is be burned due to the lack of physical evidence.

I have the oil changed every 10,000 miles and always use fully synthetic oil from a reputable manufacturer.

Some observations that I have noticed is that if I accelerate really hard from a junction there is quite a lot of smoke if I have been cruising or driving in traffic for a period of time.

When I start up there is no cloud of smoke.

When I check the oil using the dip-stick I have noticed that there is oil pooling on the engine stop device, indicating that oil is getting in to the induction side of the manifold.

The car is performing as well as she has always done – lots of poke, and good fuel consumption (48 MPG typically). There is no smoke if the car is driven hard except the initial burst after leaving a built up area.

Any ideas how the oil might be getting in to the induction side of the system?

Is this normal for this engine type – (after all 250 ml oil per 5000 miles is not a huge loss)?

Am I worrying unnecessarily?

Not knowing diesel engines all that well, I am guessing that the oil is coming from the turbo oil seals. This engine has always had to be topped up between oil changes, but the rate of consumption has defiantly increased over the last 10 months.

Thanks in advance for any hints or suggestions…
2005 Scenic 1.9Dci 120 Exception

AlexB
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Currently Drives:: Renaultsport R.S.250 Cup

Re: 1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

Postby AlexB » Wed Feb 04, 2009 2:53 pm

It is not a lot if you drive hard. The oil spray gets sucked into the positive crankshaft ventilation (PCV) system and goes directly in the intake duct just in front of the turbo compressor. The seals in the turbo may also leak at idle, as they are of labyrinth type and need speed to operate. Check the PCV circuit just in case -- it may cause excessive pressure inside the crankcase thus causing seals to leak.
AlexB
(no, a different AlexB)

Husky_Dog
Learner Driver
Posts: 79
Joined: Mon Oct 24, 2005 1:43 pm
Location: Norwich, UK

Re: 1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

Postby Husky_Dog » Wed Feb 04, 2009 5:42 pm

Thanks Alex...
I think you have answered exactly why the oil consumption rate has gone up for me. I used to live in Luxembourg, and every journey was minimum time spent at idle, and mainly motorway driving at 60 to 80 mph. Ten months ago I moved back to UK (with a left hooker too ) and now spend a great deal of time stuck in commuter traffic with the engine at idle speed.

Is it better to drive in a lower gear to keep the engine rpm up, or does this oil leakage only occur when below 860 rpm (idle)?

I don’t thrash the car all the time, but like to clear the cobwebs once in a while.

Is there any point of allowing the engine to idle after a journey? I must admit as soon as I get the car to my destination I hit the STOP button straight away.

Must admit I don’t think there is anything seriously wrong as the old girl is really performing well given her change of heated garage back in Luxembourg, to living ruff outside these days and never garaged.

I have had a look at the PCV couplings and all pipes are in place, and no perished pipes.

Thanks for the information. I’ll stop worrying about this now.
2005 Scenic 1.9Dci 120 Exception

AlexB
Driving Legend
Posts: 4308
Joined: Tue Mar 22, 2005 8:17 pm
Currently Drives:: Renaultsport R.S.250 Cup

Re: 1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

Postby AlexB » Thu Feb 05, 2009 10:37 am

Hello Husky_Dog,

I'll try to answer briefly as I don't have much time at hand now.

-- The turbine speed depends on both the exhaust gas flow (revs+calculated load) and the VGT actuator control (calculated load). The latter is higher when you floor the accelerator down at low revs. The range of VGT control is reasonably wide, so it might be OK to drive in low revs (1200rpm and above). It is impossible to avoid a minor loss of oil, as one needs to warm up the engine anyway -- I don't see any danger here.

-- Thrashing. It only makes sense after at least 15 minutes of fast motorway, when the turbo and cat become hot. By thrashing I mean flooring it down and taking the revs to 4000rpm. This will burn out soot in the cat, suck in the oil deposited in the intercooler/pipes (which become hot under boost) and to some extent clean the loose soot in the hot part of the turbo. Don't do it with bad oil, air filter, belts or under suspected intercooler/pressure control failure.

-- No (IMHO). The turbo in a diesel cools down fast by the air flow pumped through the engine under reduced loads (as opposed to throttled petrol engines). So, just gently slow down by lifting up your right foot and drive the last meters at 1500rpm without using any acceleration.

-- Heated garages vs street parking. A cold engine consumes much more fuel and destroys its own oil in no time. Consider frequent oil changes and do the blotter test occasionally (1 drop of oil from the dipstick on a business card, leave it in a warm place for 5-12 hours, watch for rings and a sticky centre). The best oils for us (IMHO again) are MB229.5 AND Xw40.

-- PCV. I meant to make sure it is not blocked inside by polymerised oil. This should not happen with synthetic oils.
AlexB
(no, a different AlexB)

Woody Woo
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Re: 1.9 DCi - Consuming oil at a rate of 250ml per 5000 miles

Postby Woody Woo » Fri Feb 13, 2009 5:09 pm

That equals about 1 litre every 20000 miles. Nothing to worry about.





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