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I've got a 2011 European-spec VW Golf Mk6 Variant with a 2.0 TDI engine (CFHC engine code, Euro 5 emissions standard, equipped with a DPF; no AdBlue, no 4Motion) with almost 200.000 km (roughly 120k miles) on the clock.

I've bought the car 5 years ago with a mileage of 160.000 km and I've been using 5W-30 engine oil ever since. However, this year, my backyard mechanic has reccomended me to switch to 5W-40 engine oil due to my mileage, claiming that it will protect the engine in the long run. I accepted.

Was this the right thing to do ? Will this have any negative consequences in the long run ? I'm more concerned about the car's (and more specifically, the engine's) longevity and less concerned about the fuel economy.

If it matters, I live in Eastern Europe, in an area with a fairly moderate climate, so I won't be driving in very cold wheather.

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    I'd personally recommend sticking with the manufacture specified oil. Sometimes there is variance in their recommendations. For instance, my motorcycle recommends 10w-30 in cold weather, and 10w-40 when it's hot. As the various tolerances in bearings etc. increase with wear, running a thicker oil will help maintain oil pressure. However, that car doesn't have that many miles, and I personally doubt that running a thicker oil is necessary. (Opinions on this will vary.) – the_storyteller Oct 30 '20 at 18:13
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Will changing to the 5w-40 hurt the engine? Most likely not. Should you change to it? I my humble opinion, no. Here's the thing ... the manufacturer has said 5w-30 (assuming that is correct) is the proper weight oil for the engine. This means all of the tolerances and how the engine runs is setup to match the 5w-30 weight oil. By using the heavier oil, you're actually putting more strain on the engine, which makes fuel mileage suffer. Also, it means the thicker oil will will be harder to push through to your turbocharger on the engine, which could cause a bit of a starvation issue, which might shorten its lifespan.

Bottom line here is, if the engine is in bad enough shape to need to upgrade to a higher weight oil, you probably need to think about changing the engine. If you have kept up with your maintenance, more than likely this is not the case. Changing the oil weight based solely on the mileage of the vehicle is not the right way of doing things.

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Summary: Your engine appears to require the "VW 507 00" oil specification and No 5w-40 oils are on the Audi usa list of approved oils meeting that spec, so I would not recommend using a different oil.


For your 2.0L Turbo diesel engine, you are better off sticking with the manufacturer's recommended oil weight and oil rating. In fact, according to Audi, using the wrong oil could damage your engine. (See link below).

Check your owner's manual to see the specific VW oil rating that your engine requires.

Update: I found a site (link below) that explains quite a bit about VW TDI oil specs. Most notably, it ends with this observation about oils for TDI engines:

Summary

Simple enough. If your car:

Has a rotary injection pump, use oil that meets VW’s 505.00 standard

Is a PD, use oil that meets VW’s 505.01 standard

Is a Common Rail, use oil that meets VW’s 507.00 standard

source: https://idpartsblog.com/2014/07/15/tdi-oil-specifications/

Your car is one of the "Common Rail" engines which require VW 507.00 oil, and while some different (and earlier) VW oil specs allow 5w40 or other weights, your car's oil specification requires a high quality synthetic oil, and only in 5w30 weight.

As the link above states, TDI engines are very hard on oil and drive components, requiring an oil suspends soot well, lubricates the cams and other parts well under high pressure and strain, and also does not leave deposits on the cylinder walls, on the pistons or on the piston rings, so using the right oil can be critical to longevity in your engine.


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More information and background...

Audi/VW are very specific about which brands and weights of oils meet specific VW/Audi standards. For example, according to this Technical Service Bulletin from Audi USA:

https://www.audiusa.com/content/dam/audiusa/Documents/Audi-2017-Technical-Service-Bulletin-1.22.2018.pdf

While that list shows that the "VW 502 00" oil standard can be met by multiple different weights of Castrol oil including :

  • VW 502 00 Castrol SLX Professional Longtec SAE 0W-40
  • VW 502 00 Castrol SLX Professional OE SAE 5W-30
  • VW 502 00 Castrol Syntec European Formula SAE 0W-30
  • VW 502 00 Castrol TXT 505 01 SAE 5W-40
  • VW 502 00 Castrol Syntec SAE 5W-40

Note that for the "VW 504 00 / 507 00" oil specification, while 17 different oils are listed, ALL of the 17 oils listed are SAE 5W-30 ONLY.

Audio was very specific in testing and specifying oils, so you would be well advised to consult your owner's manual to look up the correct VW oil spec for your particular engine, and only use an approved oil brand, type and weight.

It must have taken a fair amount of engineering and probably testing for VW/Audi to determine these oil specifications and compile a list, and given the level of specificity and detail in the different oil specifications, I would not recommend deviating from their specification.

It's safe to assume that the manufacturer made these recommendations for a good reason. We can only hypothesize why, but it could be related to known weaknesses or known failure modes with the engine, and the recommendations may very well be there to try to minimize issues from known failure modes (more info and a link are below, which is what leads me to take an educated guess that the oil specifications could be critically important to the longevity of your VW TDI engine.) -- although I will also concede that, especially for VW/Audi TDI engines, it also could be related to regulatory issues such as fuel economy requirements and emissions and pollution control... again, without more specifics one can only speculate... but if it were my car and my engine, I would tend to be cautious and stick to the specification and only the specification.

Also be aware that your particular engine sometimes suffers from a problem related to the failure of a "hexagon gear" that drives the oil pump.

You should ask your mechanic about this issue, and determine the cost and whether it makes sense to replace the oil pump and related parts as preventative maintenance, since a failure can ruin the engine.

As a reference see this site: https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php - (c) TorqueCars

Which states in part:

The ... problem is in the module itself, how it drives the oil pump, this is done by a small hexagon that also breaks because of the wear.

... the hexagon [issue] is still present in newer CR engines [Note: your engine is a 'newer CR engine', as opposed to the older 'PD' engines], but this time not just in the Passat, A4/A6 and SuperB. The only engine we are aware of that doesn’t use the balance shaft module is the 110HP 2.0 TDI(CBDC) [Not your engine]. Luckily enough there is a solution, for the PD and CR engines. It is replacing the balance shaft module for a chain driven oil pump as seen in other TDI engines. The 140hp 2.0 8v PD TDI (BMM) for example has that oil pump and it has been flawless.-- Read more at: https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php - (c) TorqueCars

Your engine is considered one of the "newer CR" engines... so at least be aware that while VW/Audio changed the design from earlier engines, and although VW made the hexagon shaped drive gear stronger, it appears that this part still has a tendency to fail, it just lasts longer before failing, and their is a preventative fix that at least some people recommend.

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