I've got a '88 300 TE with 145k on the odo. Burns maybe a quart every 3-4k of Mobil 1 15W-50 (run it year-round in New England). Runs like a top. What are the first signs that the seals (and probably guides) are going...is it solely oil consumption? And if doing the seals, do you pretty much always do the guides since they have about the same lifespan? Or, if you do the seals can you get away without doing the guides for awhile?
Also, the guides involve pulling the head on an M103 motor, right?
Thanks in advance for any input.