Im also suprised you have no oil concumption on a high miles GTi when using 0-40 Mobil 1. maybe Mobil 1 Motorsport (which is a 10w or 15w i seem to recall) would suprise me less, but both are a tad of overkill on an older vw engine. Older Porsches tend to drink it a bit & its finds it way out of the engine in all sorts of places that a 10-40 semi doesnt, both in consumption & oil leaks. Even new AMG Mercs have a bit of a liking for drinking mob 1 0-40, yet when a 10-40 semi synth was used (castrol GTX magnaT) oil consumption was negligable. Not sure who makes quantum for VAG nowadays, but 10 yrs ago it all used to be Silkoline oil.
Someone on here said that Quantum was made by Esso. Oil IS all about personal choice and I feel that fully synth is overkill in these engines for road use in standard tune. You can use cheap oil in an engine so long as you change it very regularly, which defeats the object. Synta Silver gives good protection in engines that are driven "properly" over reasonable oil change intervals. I drop it every 5K but in honesty it is still pretty clean and would be happy enough for another couple of K without worries. Warming the oil is imperative and caning cold engines is probably responsible for more engine wear than all other factors put together.
I'm the one who's surprised here! I thought all 40 weight multis were the same viscosity at high temperature, regardless of their "winter" rating. The only thing I can think of is that the "rated" temp is higher than GTi's normally run, in which case it WOULD be thinner at that lower temp. But, if it was too thin, surely the oil temp would get high due to increased friction from loss of oil film thickness? Max temp I've ever had is 112C on French motorway cruising at 90 for an hour or two in 30C outside temp. But it says in the instructions don't let it get above 140 - so I wasn't worried. However, I confirm - 197k PB engine - Mobil 1 every 5k for past 100k+ - and uses about 1/2 litre between changes (i.e. doesn't need topping up) and doesn't smoke whatsoever. Does anyone know the two rating temps of multigrade oils, i.e. the low "W - not thicker than" temp and the high "not thinneer than" temp?
0 degrees for the winter designation, 100 degrees for the hot designation. Both in centigrade. Any oil, whether 0w50 or 30w50 should have the same viscosity at running temp, assuming the running temps are identical....
I used Mobil 1 0-40w for two periods (14k miles) on my car. It was a hopeless waste of money. Not only was it 29 a time per change. I'd use insane amounts of oil per change. I drove from Bristol to Middlesbrough (it was on full when I left), and when I arrived there was no marking on the dipstick. I hadn't even gone above 80mph on the whole 4.5hr journey up. I'm sure it has its place, but not in the older VW engines. Edited by: Tuff Schmitt
. That's exactly my understanding - and cheers for the temps - so a GTi is right on the running temp for the grade! I just don't understand why some engines seem to lose it - all I know is that mine doesn't and I'll carry on with it. Cheers Guys, this has been an interesting one. I have to say - and I know I'm not the first - this is a great forum!
There may well be a difference in the viscosity curves between the oils, so an engine running at (example) 85 degrees oil temp with one oil, may actually be running a thinner oil than an engine running at the same temp with a different oil - the viscosity/temp curves will be different depending on what viscosity modifiers are in the oil. Unless they are bang on the 100 degree or zero degree mark, there's no specification for how thick the oil should be outside those temps. Could be the explanation, I suppose......
Maybe your oil temp was higher than 100, so the oil was thinner than it may have been with a different oil at the same running temperature..... Or maybe you left the sump plug out.
