I wanna use a non VW approved "thin" oil in my GTI

[Shannow]

Originally Posted By: KrisZ
You're thinking of heat generated by friction, but in the engine we have controlled explosions happening in each cylinder every second revolution of the crank. That's the main source of heat, not the internal friction. Increase the RPM and the number of explosions also increases, therefore the heat generated also has to increase.
That is why engines have to be idled or driven at speeds where the engine RPM is low in order to cool down the oil in turbocharged engines for example.


No, the greatest contributor to oil temperature rise is the oil shear itself, nor the number of controlled explosions.

In my Caprice, I can increase oil temperature from 100C to 135C for exactly the same road speed/trip by holding it in "2" rather than "D", yes, marginally more fuel flow because of inefficiencies, but the same tractive power output...just more internal friction.

another e.g. warmup phase...this is simply the oil temperature rise during extended cranking...with absolutely no "controlled explosions" taking place...frictional work only.

Here's a depiction of heat being GENERATED in main and big end bearings, requiring it to be transmitted UP the conrod, rather than the usual depiction and misconception that the oil is "carrying away" the heat of combustion.

 

[Kuato]

Originally Posted By: skyactiv
The VW GTI in my signature is no longer under warranty. I think VW is living in the dark ages requiring approved VW oil specs to have a minimum HTHS value of 3.5. If I were to use Quaker State Ultimate Durability 5W30, would I have more wear vs using something like a VW approved oil such as Castrol Edge Titanium 0W40? I'm not doing VW's 10K OCI's as outlined in the owners manual. I have been doing 5K OCI's on my GTI.


Until you get a UOA to compare the oils, it is all speculation.

 

[KrisZ]

Thanks Shannow for the graph. Yeah, so much got oil carrying away heat, but still we are talking roughly 400 watts here, but over what time? Is it per minute? If yes, then it's a good chunk of heat.

And from the first graph, notice hot it flattens as the starting oil temp is higher? It makes perfect sense for the very cold and viscous oil to have a very large heat gain just from it being sheared, but those shear forces are much less the closer we get to the operating temp.

 

[Shannow]

Originally Posted By: KrisZ
Thanks Shannow for the graph. Yeah, so much got oil carrying away heat, but still we are talking roughly 400 watts here, but over what time? Is it per minute? If yes, then it's a good chunk of heat.

And from the first graph, notice hot it flattens as the starting oil temp is higher? It makes perfect sense for the very cold and viscous oil to have a very large heat gain just from it being sheared, but those shear forces are much less the closer we get to the operating temp.


Yep, good points...it's power, so the flow is watts, joules per second, so there's no need for a time period.

Per your first point, here's one that demonstrates warmup well, with the wasted energy (heat) tapering off as the oil warms.

Other one to show wasted energy (heat generation within the oil) at different revs.

 

[fdcg27]

If I owned a basic VW with the old 2.slow, the 2.5l gas five or one of the lower powered versions of the 1.8t, I'd probably use any 5W-30 syn and call it good.
There was a long-banned member here who experimented with syn 5W-30s in various VW 1.8t engines who published good UOAs from these engines using these oils.
If I owned a VW with a highly stressed high specific output engine like yours, I'd stick with the recommended oil.
M1 0W-40 checks all of the boxes and is cheap and readily available.
Nothing to gain from using something thinner and maybe much to lose.

 

[Delta]

Originally Posted By: fdcg27
If I owned a basic VW with the old 2.slow, the 2.5l gas five or one of the lower powered versions of the 1.8t,


I wouldn't even use nothing other than xW40 in the 2.5. It's way too high strung on the highway (3300RPM's at 80)

 

[fdcg27]

That's pretty short gearing for a modern mainstream family sedan.

 

[dlundblad]

I'm still failing to see the point of OP not wanting to use a VW approved oil. I see no savings whatsoever. M1 0w40 is $22.xx at WM. QSUD is what $2-$3 cheaper?

This is a main reason used VW/ Audis have a poor reputation IMO.

 

[Delta]

Originally Posted By: fdcg27
That's pretty short gearing for a modern mainstream family sedan.


That is with the 5 speed manual, the auto is a traditional 6 speed. Ironically it will get about 34mpg (93 octane) on the highway. Right in the torque band so no downshifting is required. It will actually scoot good in 5th gear.

 

[fdcg27]

Yep, short gearing does have its advantages.
Our newer Accord, which gives about 31 mph/K in top, feels dead when trying to accelerate from even 80 mph without allowing a downshift while my old BMW, which is geared even shorter than your VW, is lively at anything above sixty or so in fifth.

 

[fdcg27]

You've posted this before and it is very interesting.
I've always thought that the only advantage of tall gearing was in reduced pumping losses.
If higher revs produce more heat and that heat can only come from friction and work must be done to overcome that friction, then the power for that work can only come from fuel consumed.
Therefore, taller gearing resulting in lower revs must save fuel through reduced frictional losses as well as reduced pumping losses.

 

[edyvw]

Originally Posted By: fdcg27
If I owned a basic VW with the old 2.slow, the 2.5l gas five or one of the lower powered versions of the 1.8t, I'd probably use any 5W-30 syn and call it good.
There was a long-banned member here who experimented with syn 5W-30s in various VW 1.8t engines who published good UOAs from these engines using these oils.
If I owned a VW with a highly stressed high specific output engine like yours, I'd stick with the recommended oil.
M1 0W-40 checks all of the boxes and is cheap and readily available.
Nothing to gain from using something thinner and maybe much to lose.

My friend's A4 1.8T with 180hp had a sludge bomb after 80K using M1 5W30 "Full" synthetic. Changed every 5K.
I on other hand had Passat 1.8T 170hp that I sold with 105K. At 95K chain was replaced (usual problem on 1.8T) and engine was clean like brand new. Used only GC 0W30 with occasional runs of 0W40 M1 and once PU 5W40.
Unless oil meets VW 502.00 in combination with MB 229.5, BMW LL-01 I am not putting that oil in my Tiguan!