Some of the innards had come loose, producing a lot of rattling when sitting at idle.
It is a 15 year old car, no repair would be cheaper than adding oil. In Seattle I would have no problem with 20-50 and it would probably slow the oil burning by half. As far as valve seals go, if your valve seals were bad you would get a big puff of smoke on startup in the morning.
Valve seals generally make smoke at start up.
In general compression runs 160-200 psi; and cylinders within 10 psi of each other.
Thanks for that information
It’s also quite possible to have 195 PSI compression on every cylinder and still have an engine burn oil rapidly past the rings if the wiper rings are stuck, the cylinder walls glazed, etc.
That was actually the case with one of my previous cars
I had a 1971 Maverick that took a quart of oil about every 300 miles. I had the valve stem seals replaced and that reduced the oil consumption to a quart every 1200 miles. The job can be done without removing the head. The spark plug is replaced with an adapter that allows air from a compressor to be blown into the cylinder with the piston at its highest position. The allows the valve to be held in place with the compressed air while the keeper, spring and seal are removed, a new seal installed, then the spring a keeper replaced. I think the cost was under $50 back in 1974. I have no idea what this would cost today.
I wouldn’t replace the valve guide seals unless I was pretty certain that was the problem. I’d want to eliminate some of the other common possibilities first I mean. Wet/dry compression, leak down, etc. One common symptom of a valve guide seal leak is a puff of blue or dark smoke out the tail pipe immediately on starting the engine, after the car has sit parked for several hours. Then the smoke goes away completely, within a minute or two. It’s not a definite thing as the cat can mask the smoke, but if you see smoke out the tailpipe first thing in the AM, then it quickly goes away, that’s pointing to valve guide seals.
Will check compression over the weekend and try 10W-40 or 20W-50, since I’m due for an oil filter change anyway. I’ve had no smoke on starting.
Using 20W-50 oil will just accelerate engine wear at cold start-up.
It takes longer for that heavy of oil to reach critical engine components when the engine is started. So if the rings/cylinders are worn, that weight of oil will just make them wear out faster due to the lack of lubrication.
Tester