VW oil recommendation anomaly

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We see a lot of VW 1.4 16v engines come through our workshop with noisy valve train and hydraulic lifters. All the cars are using either the longlife 5w-30 oil or 10w40/5w40 502.00 oil for fixed interval recommended on all the oil company websites on their recommendation tools.

I have another technical data system which interestingly recommends the following

ENGINE: TIME/DISTANCE DEPENDENT SERVICE ( >2007)

Engine oil VW 501 01 SAE 5W-50, 10w-60 All temperatures
Engine oil VW 501 01 SAE 5W-30, 5w40, 10w-30, 10w40 Below 15 °C
Engine oil VW 501 01 SAE 15W-40, 15w50, 20w50 Above -15 °C


ENGINE: TIME/DISTANCE DEPENDENT SERVICE (2008> )

Engine oil VW 502 00 SAE 5W-30, 5w40, 10w40 All temperatures


We've put 15w40 mineral oil in my mates Golf 1.4 16v (only 60k miles) instead of 10w40 semi syn and it stopped tapping. We've put 15w50 mineral oil in one of our customers 1.4 16v's with a horrendous tap and general valve train noise and now it's all quite on the western front. I guess they had a modification done in 2007 to these engines.

My question is what is the difference between a 15w40 mineral and a 10w40 syn when at operating temp because on paper there shouldn't be one but real world there definitely is. A friend of mine has a classic car which specs 20w50, we put Motul 15w50 Ester synthetic in there and the oil light flickers at idle when hot. We put a mineral 15w50 in and it's fine.
 
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Base oil viscosity of 15W will be much higher. This is the real thickness of the oil. VI and DI are giving the boost to move it from its BOV (5-7cSt) up to the ~14cSt of a 40 grade.

15W-40s also tend to be nearer 15cSt Kv100 too.

This additional thickness will help quieten things down. Kv100 is just a measure of thickeness of oil under gravity at 100C. The engine is very different, there is no gravity flow of oil in an engine -except for draining to the sump and local temperatures vary away from the bulk ~90C oil temp.

2008 models are asking for improved oxidation performance from the oil. 501 01 to 502 requires an additional high temperature engine test on VW hardware.
 
They must have done something to the engine itself though as the viscosity vs ambient temp recommendation is different.
 
Originally Posted By: riggaz
We see a lot of VW 1.4 16v engines come through our workshop with noisy valve train and hydraulic lifters. All the cars are using either the longlife 5w-30 oil or 10w40/5w40 502.00 oil for fixed interval recommended on all the oil company websites on their recommendation tools.

I have another technical data system which interestingly recommends the following

ENGINE: TIME/DISTANCE DEPENDENT SERVICE ( >2007)

Engine oil VW 501 01 SAE 5W-50, 10w-60 All temperatures
Engine oil VW 501 01 SAE 5W-30, 5w40, 10w-30, 10w40 Below 15 °C
Engine oil VW 501 01 SAE 15W-40, 15w50, 20w50 Above -15 °C


ENGINE: TIME/DISTANCE DEPENDENT SERVICE (2008> )

Engine oil VW 502 00 SAE 5W-30, 5w40, 10w40 All temperatures


We've put 15w40 mineral oil in my mates Golf 1.4 16v (only 60k miles) instead of 10w40 semi syn and it stopped tapping. We've put 15w50 mineral oil in one of our customers 1.4 16v's with a horrendous tap and general valve train noise and now it's all quite on the western front. I guess they had a modification done in 2007 to these engines.

My question is what is the difference between a 15w40 mineral and a 10w40 syn when at operating temp because on paper there shouldn't be one but real world there definitely is. A friend of mine has a classic car which specs 20w50, we put Motul 15w50 Ester synthetic in there and the oil light flickers at idle when hot. We put a mineral 15w50 in and it's fine.


Are you sure it is valvetrain noise you hear. Those engines have massive problems with piston slap due to cold pistols(too small) that can sound alot like valvetrain noise.
 
It's definitely hydraulic lifter noise on the Golf, it stops once they've pumped up. The tap is definitely lifter noise on the Fabia 1.4 16v as well (it only has 20000 miles on the engine) but it's gone now.

As a side note, there is also a problem with the 1.2, 3 banger vw engines with excessive valve guide wear which burns the valves out. The Skoda lads in CZ have stopped using the 5w30, 5w40 and 10w40 oils and use 15w40 mineral oil in them which they say stops it. No one in CZ Skoda community buys the 1.2TSI engine as it's garbage. If they want the diesels they buy the PD engines rather than the CR engines.
 
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Interesting...

You seem to be rediscovering the joys of having heavy base oil in engine oil.

If you compare an all mineral 15W40 to a semi-synthetic 10W40, the main differences are...
1) the 15W40 will contain about 30% heavy base oil (eg Esso 600SN), the 10W40 will contain 5% if you're lucky
2) the 15W40 will have a much lower Noack volatility, typically around 7% vs 12% for the 10W40
3) the 15W40 will contain much less Viscosity Index Improver (rubber to you and me)

In the rush to low viscosity lubricants, it seems people have forgotten the magical properties of heavy base oil. I'm not sure why it's so special, I just know it is. I'm pretty much sure in my own mind that Audi could have avoided the horrendous oil consumption problems on the 2.0l TFSI had they thought a bit more about the oil they put in the engine. I also suspect that the US, which has some of the most volatile engine oils in the world and has virtually eliminated heavy base oils from PCMO, is sitting on a time bomb of their own making. We shall see...
 
What about different base oil used between 5w/10w and 15w regarding quality? Is there a high quality 15w40 made with a Group III base oil that can meet strict modern requirements. If not then why?

Riggaz,
controversially Fiat made a back specification in mid 2000s for all multivalve (hydraulic adjusters) cars that were originally specified for 10w40. Most of those engines had lifter noise on startup that was eliminated with use of 5w40 oils.

Twin Spark Alfa Romeo engine also had a bad habit of cocking oil gallery for main bearings on cylinder 2. This was attributed to a tubular exhaust manifold passing very closely to a block and heating oil in that particular gallery after shutdown.

It seems this problem mostly occurred while people were using 10w40 on 20k km OCI, and it was cured with 5w40 oils.
 
You can't make a full Group III 15W40. Even a full Group III 10W40 is only just about possible. The problem is that the hydrocracking process they use to make Group III tends to 'destroy' heavy base stocks. The reason that full synthetics are either 5W or 0W is that's usually all you can make with them.
 
It tends to be easier to make a full synthetic HDDO 10W40 because there's generally quite a lot more additive in an HDDO; particularly ashless dispersant.
 
Not sure I can answer this properly as motorcycle oils aren't my thing. However a couple of things come to mind. First off, motorcycle oils are very small volume products compared to mainstream PCMO & HDDO. They also tend to command a high price premium. This being so, you have more flexibility to plop in some super expensive 'heavy' to make the viscometric balance work. The second thing that comes to mind is that these oils could be 'slack' 10W40s as opposed to a 'tight' 10W40s; in other words one where the oil's CCS is close to the 5W limit but not quite. You can play these games on motorcycle in a way that, for various reasons, you can't with PCMO & HDDO.
 
I agree, VAG are using the longlife service as a sales tool which obviously goes hand in hand with the 5w-30 LL3 oil.

What problems will arise for eliminating heavy base oils?
 
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