2.2 D4D Diesel Oil Consumption

[PumaWestie]

I'm not wishing to dredge up this again as It is well documented on here about the oil consumption on the 2AD engines fitted to the early 2006 / 2007 RAV 4 vehicles and about the warranty that Toyota offered to fit replacement engines but does anyone actually know what the root cause of the issue is?

Is it a design fault?

Is it related to fully synthetic oil not allowing the engines to bed in properly when first used?

Is it related to driving technique?

Could it be related to the EGR valve issues causing dirty intake fumes to clogg the piston rings?

Just curious and if there's an alternative to engine replacement. Some on here suggest running 5w40 oil instead of 5w30?

Thanks

John

[Devon Aygo]

The oil consumption issue, burning more than 0.5lt/621miles is caused by a poorly designed piston/piston ring ( design fault ) and none of the other ideas you mention above.

Fully synthetic oil is not an issue, poor quality or the wrong specification oils are! See the pined section at the top of the forum to find the correct specs for your car.

A poor driving technique won't help , but bad driving habits of repeated short trips can exaggerate the issue.

The EGR suffers excessive carbonisation due to the oil burning and prolonged use of lower quality supermarket fuels.

5w30 is the correct grade for UK climate.

[bigend]

If you read the handbook there are more permutations of grades of oil, not only 5w30.

Keith

[Devon Aygo]

If you read the handbook there are more permutations of grades of oil, not only 5w30.

Keith

The hand book lists other grades for different climates, the correct grade in the UK is 5w30

[bigend]

The handbook shows the temp range of the different oils, so if the temp is in range there is no reason to not use them. In fact' if you read the book they only say it is the prefered one.

Keith

[kencat]

Think a lot off it stems from excessive backpressure in the engine ! The 150 bhp is redesigned ( less backpressure , it's also got new pistons , injectors , egr )

[gjnorthall]

The issue is simply that manufacturers are continuously trying to reduce weight and friction in order to improve fuel economy and reduce emissions. Piston rings are probably half the height that they were 25 years ago and things are often on a knife-edge. It's not the first time that Toyota have faced this problem - around 10 years ago there was a big problem with oil consumption on the 1.8VVT-i petrol engine. A steel strengthener had been added to the slimmed down piston - differential expansion in some instances led to the bores wearing oval. As an aside - increased back-pressure tends to reduce oil consumption.