Oil consumption on 1990 190e 2.6
I know this subject has been covered pretty thoroughly, but I couldn't find much on my particular problem. I bought a very nice 1990 190e 2.6 early this year with 84,000 miles on it. Owned by elderly couple since new, and their driving habits could be part of my problem. Within a couple of months, discovered that car was using one quart of oil every 800-900 miles. Having driving mostly japanese cars in the past, I was a bit alarmed. After checking on this forum, I learned about the likelihood of bad valve stem seals, so I had them done about one month ago. Just before this, I changed the oil and put in Valvoline Maxlife 20W50 to help address the problem. I haven't driven the car much since the oil change/valve seal replacement, but it appears to be using at least as much oil as before, maybe even more (one quart in 600?). Now I am really feeling bad. Compression tests shows all six cylinders between 145-150 and leakdown test shows all six between 14-20%, which I was told was ok. Also was told by mechanic that spark plugs looked fine.
Where do I go from here? I use a private mechanic who has a good reputation with German cars. He is the one who did the valve stem seals for me. Just out of curiousity, I called the local MB dealer to ask them about this problem. Service manager stated that if the seal replacement didn't do the job, then it is possible that the valve guides are damaged and I may need a complete valve job. I questioned this as the car only has 85,000 miles, but he said if the car was driven on mostly short trips, carbon buildup could damage the guides even with low mileage. He also stated that by using the Valvoline Maxlife oil, I may have cleaned out some deposits that were actually helping the car not use as much oil, thus, causing an increase in consumption.
Anyone have any thoughts or suggestions? Short of a valve job, should I try different brands/viscosities of oil. I have heard that these cars react differently to different oils. Any comments good or bad on this Valvoline Maxlife product?