GC dissolved light sludge in a VW VR6!

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Jul 13, 2003
Car History:2000 GTI VR6 bought used with 28,500 miles on it.No previous records.

In the oil filter cartridge housing base and in a small spot visable under the oil cap was sludge.

At 29,190 miles GC went in.Drained it today with 2830 miles on it.

When I pulled the housing to remove the filter(which looked kinda dirty but nothing big in the pleats)I noticed the sludge that sat at the bottom of housing was gone

Sample is going out tommorow.
Very short run for GC. Your UOA will be interesting. If it was performing an engine-wide clean-up job, there should be signs of that in the results. Was this griminess the reason for the early switch, or something else? It looks from my mid-term UOA like GC will have no problem going 10k miles in my G35, but it has a healthy, young, and spotless clean engine. Can you see down your oil filler opening? If so, what's there?
Yeah it's short but not knowing the history of the engine I wanted to cut the interval short to get a sample out

There is some sludge build up in a spot under the valve cover where there seems to be poor oil flow
.It was very black and looked "stuck" on there.
I can see metal now where before I could only see the sludge before.It's not 100% cleaned out(more like 70%)but the oil has done a darn good job for a 3K run,especially in the winter

I am really impressed by the cleaning effect synthetic oil had on my engine in 3K miles.

Currently running a mix of Chevron dino,4qts 10W40 with 2 qts 10W30,fresh filter.This will be a short interval flush.I don't know what i'll use next
I like GC but I got a feeling this stuff ain't gonna be around for long.

I might go to M1 5W30 or M1 0W40 next time out.

A couple of years ago, Bob (the oil guy) did a experiment with a number of oils and additives in beakers, I do not remember which additives but I do remember that at least two of the beakers (or containers) had synthetic oil, one container had Mobil 1, the other Amsoil, and some of the containers had petroleum oil.

Bob placed rusted or corroded parts and/or particles in the containers, the containers with Mobil 1 & Amsoil oil had dissolved the particles,
also one of the additives dissolved the parts, dirt?.

This test shed some light on how the synthetic oils could help dissolve deposits in the engine.

I could not find the link, does anyone know where to find this link, I know there were lots of pictures showing the containers with the oils and additives with the particles or parts in them, if anyone finds this link please post here, thanks.

I found the link, it is:

web page

Bob used engine valve seals in the beakers, the various oils & additives dissolved the crud on the seals, thought you would like to see and read.

[ January 28, 2005, 02:35 PM: Message edited by: Bill ]
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