dorsal900

I'm about to change the oil on my 1996 A4 2.8 QM. Since new, the car has used oil, i.e. a quart in 1000 miles - this has gotten somewhat worse, especially with a few small leaks . I have been using Shell Rotella-T 5W-40. Is this the best choice or is Castrol Synthetic, which I recall may be better for oil consumption?

Before I do this change, is there some flush I should try to "free the oil control rings", i.e. Seafoam or other?

moribundman

Those contain seal conditioners that may help reduce leakage and aid sealing. A good choice would be Valvoline Maxlife 10W-40 (Meets ACEA A3, so it's fine for the 12v).

If you want to the clean ring land, a Seafoam treatment (or simple water decarbonization) may help. I'm not in favor of such harsh cleaning methods, but people have reported good results. Do at your own risk.

A milder cleaning attempt, although noticeable results regarding a cleaner ring and groove area are questionable, would be the use of either a high ester oil (Red Line -- expensive) or a good mixed fleet oil like Chevron Delo 400 15W-40 (also available as 5W-40) or Rotella T, which you mention. How is oil consumption with the Rotella?

dorsal900

Hi Mori! Before I started running the Rotella T, I used Delo 400 15W-40, switched before winter in Chicago.

Every couple of weeks I need to add a half-quart of oil. The engine does have some leakage I replaced the valve cover gaskets, which helped a lot, it looks like I will need to replace the lower oil pan gasket too (at a minimum). It appears to be leaking there, but it's hard to tell because it's out in the air flow while driving.

Is Valvoline MaxLife 10W-40 a synthetic? This car sees a lot of city driving, and when I changed the oil after one non-synthetic fill lumpy gravy (sludge?) came out, so I'm now very cautious about what I put in there.

moribundman

"when I changed the oil after one non-synthetic fill lumpy gravy (sludge?) came out"

That's odd, because the oil gets constantly filtered and the crud remains in the oil filter.

Sludge does not come from using mineral oil. It comes from using the oil too long and from putting to much (thermal) stress on it. A non-functional PCV system and air leaks contribute greatly to sludge production. Introduction of moisture into the oil (short distance driving) causes sludging. If you began to see sludge after switching to an HDEO like Delo or Rotella, it's likely that these oils did some cleaning, but again, why didn't the oil filter catch the loosened stuff? Did you cut the filter open?

Valvoline Maxlife 10W-40 is a blend of mineral and synthetic oil.

dorsal900

Yes, I need to fix the leak(s). Now that it looks like we are finally done with snow here, I will sign myself up for the oil pan job where I need to lie on my back on the ground for a couple of hours .

At the time of the "lumpy gravy" oil change, my wife was the primary driver of the A4 and used it for lots of short trips. She had also taken it to Jiffy Lube and got dino oil put in, and probably drove it further between changes than her harsh usage required. One thing that I will give our local Jiffy Lube is that they used Mann filters (and charged extra for them) on the A4. I have no idea why the filter didn't catch the sludge, I have never cut a filter open.

After enough missing belly pan screws, lumpy oil, overcharges for additional oil ("your car takes six quarts of oil" - no it doesn't), over-aggressive tightening of the drain plug and filter, etc., I now change the oil myself every time using synthetic.