280sel4.5 valve guides

True to form, my 4.5 needs it's valve guides replaced. It currently consumes oil at a rate of 1 qt./tank. The plugs were lightly coated with ash deposits last time I checked. How much worse will this condition get, and will driveability ever get to the point where the engine won't idle or run right? It actually runs fine now. I've been quoted $2800 turnkey on a head job. One can buy alot of 10w40 for that. I do feel guilty about the air quality directly behind my belching tailpipe, but I need to cash a few more paychecks.

[stevebfl]

If you have uniform carbon deposits on all sparkplugs, I would suggest replacing just the seals.

Don't do it till you are ready to go all the way as the only reason not to only replace the seals is that the guides can be worn out both inside and at the top where the seals grabs. I have seen many of the old seals wear the top right off the guide from moving up and down with the valve.

Doing just the seals is a 5-6 hour job two valve cover gaskets and two seal sets (not much money - only use genuine MB)