Hi all. I bought a Mk3 1.8 (06 plate, 69k miles) last July and whilst I love driving it it uses way too much oil. If I top up the oil by the time I’ve driven 150 miles the level is on the bottom of the dipstick. I’ve read the Mk3 can use a bit of oil but this is crazy, I can’t do a 200 mile journey without stopping to add oil. My brother is an experienced mechanic and has tried various things. We changed from 5/30 to 10/40 oil (did a flush too, new filter obviously), and I also had the PCV valve replaced. Last week we tried a tip we found online where Sea Foam liquid is put down the plug holes and left to do it’s stuff. On 1 of the cylinders the liquid just sat there as you’d expect but the other 3 it kept just draining away, we assume this means the oil control rings are stuck. I hope that makes sense, my brother is the technical one not me! There’s no obvious leaks anywhere on the engine, and it sailed through the emissions check on the MOT; smoke from exhaust appears normal.
Any clues anyone or am I resigned to having to get the thing rebuilt to sort the control rings out?
There have been previous threads on this forum on this subject. Just search NC oil consumption.
My first action if you have not already done it is to perform a compression test, first dry then wet to check for bore and valve seal wear.
I assume that there is no sign of leakage from the sump, filter or crankshaft seals.
You may only see blue smoke in the exhaust at start up when the cat is cold. Once the cat is hot it will vaporise the oil. However you do need to remedy the problem as burning this quantity of oil will soon contaminate the cat.
Right then. After the Sea Foam trick it did 250 miles without using any oil. Then I did a 120 miles round trip the next day and the dipstick just had a tiny amount on the bottom, below the dot. All very strange.
Brother then tried again using Tunap, and this time he drained oil, and kept recycling the Tunap through the 4 bores and by the end of the week the liquid was not draining past the pistons so it seemed like the oil rings had come unstuck. The car definitely drives better and we were hoping all was now well. After monitoring oil usage it’s just gone from top dot to bottom dot of dipstick after 290 miles, so it’s better but still using far too much (about 3 litres per thousand miles-ish?!). I’ve been quoted £550 for a refurb engine, or £1700 for my own engine rebuilt. It’s a good job I enjoy driving this car as it’s been a royal pain in the backside since I bought it! For now I’ll keep monitoring it and hope it magically improves the more I drive it.
As I have said before change the oil regularly using good quality oil will prevent the oil control rings from carboning up resulting in oil consumption.
We work closely with an oil company and the cheaper the oil you buy the less additives it will have to prevent the above.
Totally, we’ll be changing oil frequently and using an oil flush every time too. I guess the problems have come from poor maintenance by previous owners. I thought I’d update this thread in case other NC owners have similar issues, although it seems I’ve been pretty unlucky. I ADORE driving this thing though
Years ago my dad ran a garage looking after 150 diesel vans, he had a bulk tank of Shell rotella which was a very high detergent oil. New cars got a sump full of this & were run for 2-3k. When you drained them it took loads of gunk with it. You then changed filter & put some decent oil in, typically Duckhams or Castrol the oil then stayed clean for ages.
It certainly freed the rings up.
