2017 VW Golf 1.8T - Castrol Edge 5w40 - 6,800 miles

[BurntMusic]

Here's last years UOA for anyone interested. I had my oil changed at the dealership (apartment life, otherwise I'd love to do it myself) and they used Castrol Edge 5w40. Due to the pandemic, my driving was severely shortened this year since I am now working from home. I would say 75% of the 6,800 miles here are city driving, the rest is highway. It looks fine to me, just typical fuel dilution which I noticed when I was transferring the oil into the correct container...

Oil is on the thin side due to dilution just like the last change. I suspect this might be due to the tech turning on the car, driving it to the lift, then turning it off, not giving any time for the fuel in the oil to dissipate. It's ok. The car has been 100% problem free this past year otherwise.

Next service is the 40,000 mile service which involves oil change, spark plugs, cabin/air filters (which I do every 10k out of boredom) and the usual inspection.

 

[Jetronic]

Not much fuel can make it into the oil in the time it takes to get from the parking lot onto the lift...

 

[skyactiv]

That is a very good looking UOA for a VW.

 

[KCJeep]

That's dealer Castrol all right, the Wally's version has Ti and some boron in it IIRC. UOA looks good, there definitely is fuel as that is lower viscosity than normal for Castrol 5w40.

Do you have a DSG? That should be included in your 40k service.

 

[Boomer]

Yep, definitely service the DSG tranny at 40,000 miles!

 

[BurntMusic]

Not much fuel can make it into the oil in the time it takes to get from the parking lot onto the lift...

I must be mistaken how it gets into the oil then.

That's dealer Castrol all right, the Wally's version has Ti and some boron in it IIRC. UOA looks good, there definitely is fuel as that is lower viscosity than normal for Castrol 5w40.

Do you have a DSG? That should be included in your 40k service.

Nah, this model year for the Golf (non-GTI) is just a standard 6-speed torque converted Aisin 09G tranny. You're correct that the DSG service is every 40k though. The only service my particular transmission needs is a drain and fill every 80k miles with no mention of tranny filter replacement. I doubt I'll keep the car that long though. I heard Mazda is bringing an inline-6 to their mazda 6 in the coming years. I'm keeping my eye out for that

Yep, definitely service the DSG tranny at 40,000 miles!

See above.

 

[Jetronic]

You have the right idea about fuel getting into the oil, but time is an important factor. Also, you can't get all fuel back out again without draining.

Here's a bunch of distillation curves, notice how the heaviest fractions of gasoline fuel (the last 20% or so) need higher temperatures than your oil will likely see in the engine and once there, stays there...

 

[BurntMusic]

So there could be maybe like 20% of the fuel in the oil remaining?