# Should I Use a Heavier Weight Oil in and Older Engine (MK4)?



## filmnoire (Sep 11, 2009)

I have a 2000 Jetta GLS with a 2.0 that has almost 150,000 miles on it. It's currently going through about a quart of oil a month (I top it off every week or two in order to maintain safe levels). There's no blue smoke, but I can't rule out that it might be burning a little in addition to leaking a little. I always put 5W30 in her, as the manual calls for, but I'm wondering if it would be safe/wise to switch to a somewhat heavier weight, due to the age of the engine (I'm not really into going with synthetic). I live in Southern California, so difficult starts due to cold weather with heavier oils isn't an issue for me like it would be in the north. Anyone have any thoughts or tried it? 

The cost of oil and what it takes to get it into the country in the first place is enough to make me want to avoid wasting any more of it, ya know? 

Thanks!


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## T Dog (May 22, 2014)

Yes, heavier oil is a good idea in the 2.0. There was a problem with the rings being installed upside-down in those engines. You should research that. If you want to reduce burning, make sure your PCV system is 100% functional, or even improved w/a catch can. Also, an intake cleaning /piston soak is going to free up those rings if they have deposits from blowby. Look at my other thread on piston soak w/mmo, even an intake cleaning with oil, then the solvents.

As for oil, you can start w/a 10w-40 hi-miles oil. QS Defy comes to mind. If that burns after it's had a chance to soother the seals (as HM oils do) then the next step is a 15w-40 HD diesel truck oil. I like Mobil 1300S, Rotella is most common. If you burn >1q 1000 miles of that, you have mechanical issues. 

There is also one other option, a 10w-30 HD diesel truck oil like Rotella and Motorcraft are common now at WalMart and autoparts stores. Motorcraft is an outstanding product, and a 10w-30 diesel oil should be stout enough to keep consumption down, while not hurting mpg. 

Maybe you may want to try the 10w-30 HD first, if that still burns, the 10w-40 HiMiles, then the 15w-40 as a last resort. If you take short driving trips, try to stick with the thinner oils. If you take long 30 min+ drives mostly, the heavier oil will serve you well. Try a bigger filter to keep capacity up and oil temps down.


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## filmnoire (Sep 11, 2009)

Wow, T-Dog. Thanks for taking the time to provide so much detailed information! :thumb up

I had no idea about the rings being installed upside down on some of these! But it doesn't really surprise me either, given how many class action suits VW saw on the MK4 series. :screwy: She's been a pretty good little car for me all things considered, but the things they got wrong are really annoying.

I did replace my PCV recently (right under the oil cap on these, oddly enough). I kept having problems with starting (which I think I've fixed by replacing the coil pack), as well as carbon (and later motor oil) building up in the intake where the air hose connects to the manifold. I've cleaned the area out pretty well, but I will definitely look up your post about piston soak, as I'm unfamiliar with the process but it sounds like a good idea.

I'll try some 10W40 high mile oil on the next 3,000 change and a bigger oil filter if I can find one. If that doesn't do the trick, I'll move on to some of your other suggestions. Again, thanks so much brother! :beer:

Cheers!


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## T Dog (May 22, 2014)

5000 miles oil change is fine, those engines are VERY easy on oil. I change 2x a year for seasons, Late Fall and Spring. It also lets me switch visc for summer/winter...here in the Northeast. Counting miles till oil change seems off to me. It'sa pretty arbitrary number, where most instances you can go way past 5000-6000 miles.....6 or 4 months just has a more satisfying feel, and it accounts for the short trip drive as well as the longer hwy driver. 

They both need a change in X amount of time, because, despite more miles, the long drives keep the oil in better condition, no sludging from short rides not getting the engine fully heated. Long drives burns off all the condensation and excess fuel from the short drives. Hey, your PCV was clogged, that says something.


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