Hi there, I'm hoping you can advise me on correcting a mistake I made.
I have a VW GLI with a 2.0 TSI that calls for VW 502/3/4 5w30 or 40 synthetic. I accidentally added our Subaru Outback oil, which is 0w20 synthetic, about 1 to 1.5 litres. I am about 5,000 km away from a service, which should be in the dead of winter. Should I worry about this, and change the oil now? Or is there an averaging effect, where 5w40 gets diluted down to 4w30 or something like that? I'm guessing not, that a part of the oil will behave differently than the rest of the oil. I've tried to read up on how viscosity works, but don't understand when thin is too thin.
Any help would be appreciated.
Used 0w20 instead of 5w40
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Originally Posted By: AVG
Hi there, I'm hoping you can advise me on correcting a mistake I made.
I have a VW GLI with a 2.0 TSI that calls for VW 502/3/4 5w30 or 40 synthetic. I accidentally added our Subaru Outback oil, which is 0w20 synthetic, about 1 to 1.5 litres. I am about 5,000 km away from a service, which should be in the dead of winter. Should I worry about this, and change the oil now? Or is there an averaging effect, where 5w40 gets diluted down to 4w30 or something like that? I'm guessing not, that a part of the oil will behave differently than the rest of the oil. I've tried to read up on how viscosity works, but don't understand when thin is too thin.
Any help would be appreciated.
The oils will be miscible (blend into each other) and will just result in a composite oil that will likely be a bit thinner than the 5W40 would have been at all temperatures. Might start just a bit better in the cold but also give you just a little bit less protection if the oil temps get very high for some reason.
If you really did blend the 0W20 with a 5W40 and 5W30 is also allowed for your engine, I'd guess there isn't that much to worry about. If it's going to drive you crazy or you just like being extra careful, then go ahead and change it.
Originally Posted By: knerml
I would change the oil. In my experience, VW/Audi turbos run hot. It's not really all that cold in Toronto.
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Just drain the oil.
Chalk it up as a mistake and fix it properly.
Listen for odd or excessive engine noise cold and hot - it she's as quiet as before then you are good to go. I would knock back the soft redline 1000 rpm short.
You likely made a 5W30, there are no "in between" numbers and available oil viscosity in the 30 grade range is all over the place.
Originally Posted By: judsonj
Here is a summary so far:
Change it
Don't change it
You probably should change it
You probably shouldn't worry about it
Hope this helps 
Wow, thanks all for the quick and lively debate! Somebody said I should expect as much. I liked hearing the techeese, and understand a bit more about oil considerations. I've gained confidence that I'm not facing imminent disaster, at least. But in the absence of consensus I am giving in to my tendency to do-what-the-dealer-tells-you. I'm overdue for new plugs anyways, so may as well do the full service now.
Originally Posted By: tig1
Can't remember who it is, but they have a MB that calls for a 40wt oil and they use M1 0-20 and their engine performs very well.
Take the car to a shop that does PCM tuning and have them install a 2000 RPM rev limiter to the PCM.
As long as the engine is kept below 2000 RPM, it should be OK.
I would change it.
I knew of a Honda tech who pumped in 5W-20 into his friend's GTI when he changed the oil. It seemed to be running fine.
1 quart of 0w-20 into a sump full of xW-30/40 won't hurt a thing. VW would warn to get the oil changed at the earliest opportunity but in all reality you might have slightly thinned out the oil and diluted the add pack a smidge. North American/Asian(ILSAC and dexos-1) oils are focused on fuel economy and passing specific tests, while European OEM/ACEA spec oils(and dexos-2) are focused on high-speed operation and more wear protection from what I interpret, with specific testing for BMW/MB/VW specs. The Europeans say that topping off with API SL-SN ILSAC-spec oil is OK in emergencies.
It's your call to change the oil or run this until you are due for a service. I'm in the camp of any oil(as long as it meets the specs) is better than none.
If it were my GLI I'd let it go until the OC is required but I would avoid 'spirited' driving (which would make the turbo hot)....0w20 synthetic most likely has a lot of POA in it's base oil so it shouldn't be a problem in Nov/Dec in Canada, IMO.
Maybe even find a way to limit the travel distance of the accelerator pedal.
If you care about your car make sure it always has a complete fill of the correct oil. Change it immediately.
Originally Posted By: Merkava_4
Take the car to a shop that does PCM tuning and have them install a 2000 RPM rev limiter to the PCM.
As long as the engine is kept below 2000 RPM, it should be OK.
Originally Posted By: Merkava_4
Maybe even find a way to limit the travel distance of the accelerator pedal.
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