I have a 95 Accord EX 4 cyl VTEC with 143,750 miles on it. I changed the oil last at 143,000 and went to a blend of 3 quarts of Havoline 5w30 and 2 quarts of M1 5w30.
750 miles later I check the oil and it's 7/8 quart low. I ran my last OCI through 5,000 miles on Havoline 5w30. I had to add about 2/3 quart after 2,000 miles. I added some M1 5w20 at that time. It stayed full until I dumped it 3,000 miles later.
I have not noticed any leakage on the ground, but I will say that I haven't looked much either, as I'm parking at work or in an apartment complex. I will see this weekend on my garage floor if I have developed a leak.
Of these 750 miles, 600 of them have been highway (60% highway, 40% Interstate). Yes, I have taken it to 4-5k rpms at times, but only for high revs, nothing sustained.
Barring a rear main seal leak that has developed, could I be seeing some of the notorius "M1 burning" ??? I just had a timing belt job, so I doubt any of those new seals are leaking. I checked out the engine compartment as best I could, but didn't see any oil. I just went over the thing last weekend, 150 miles ago.