Using thicker oil in engine with low tension rings

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Mar 6, 2004
I'm currently running Castrol RX 15w-40 in my 02 VW Jetta 2.0 and it runs good. But I hear that the modern 2.0 engine has low tension pistion rings and tighter engine clearance. So VW would reccommend a thinner oil for fuel economy. I'm running 15W-40 to reduce my oil consumption. So my question is that by running a 15W-40 in this engine, will there be any long term effects on the rings or the catalyst. Also how much change is there in the 2.0 engines of the A4 VWs compared to the previous generations? I know my wording is not accurate since I don't know too much about engines. Thanks for any replies.
Volkswagen recommends 40 weights in the 2.0 and I would stick with that.

There really were not many changes with the 2.0 between the MKIII and MKIV. The only significant changes I was aware of was the rods were increased in length and low tension rings were used. The only other minor changes were with the intake/exhaust manifold, the CCV system was moved, the ignition is now distributorless, throttle is drive by wire, etc.
You'll be absolutely fine with the Castrol 15w-40.

In regards to the piston rings, the HDEO will keep them very clean and operating properly. Ring land cleanliness is of high importance and thoroughly addressed with CI-4 lubes...

In regards to catalyst activity, yes, the higher levels of phosphorus have been said by some to reduce activity at a faster pace than a PCMO would, but you must remember this: You're passing a great deal less oil and vapor into the exhaust system in comparison to a 5w or 10w-30 PCMO.

Any particular reason you're using the Castrol though? I feel something such as Mobil Delvac 1300 is just a wee bit superior...
Well I chose Castrol RX 15W-40 because it says that provides excellent protection for gasoline engines that need ISLAC GF3. So I thought it was one of the better ones for gasoline compatible. Actually I've considered Chevron Delo 400, Pennzoil Long Life, and Mobil 1300. Probably will use that at next oil change, I like trying different stuff out.
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