This one is baffling. I mean, truly baffling.
The issue: Intermittent oil loss of at least one quart of oil. I had the oil uptake O ring and oil pump on my Denali for the usual reasons. Now the problem is even worse and has become absolutely bizarre.
OK, so if I drive 1000 miles at highway speeds I don't lose a drop of oil, but it I drive locally, I'll lose a quart in 100 mile, but it occurs at random. I check the oil in the morning and evening to verify this all. I get up in the morning, the oil is at the full mark. I drive less than 50 to 100 miles locally, go home in the evening and the oil is exactly full. The next morning I check the oil and a quart has vanished. There is no oil on the ground in the garage, and absolutely no sign of a leak anywhere. But, sitting over night, a quart of oil has vanished. This will happen every two days just like clockwork. Every two days. Sometimes a quart of oil will vanish in a 20 mile trip, no smoke, no leaks, no nothing).
There is no smoke from the tailpipe at all at any load or speed (I had someone follow me to verify, and they observed no smoke at all even when a quart vanishes in a 20 mile trip, which is another issue). We checked all the seals, no leaks; We checked the compression, and it's exactly factory specs. The spark plugs have absolutely no deposits on them whatsoever. No oil contamination of coolant and vice versa. Where is the oil going and why?
I even hung a sheet under the chassis and drove and not a speck of oil, yet a quart vanished in as little as 10 miles. And this occurs at two day intervals like clockwork. I can check the oil and not drive the vehicle for two days and at two days, a quart vanishes with not a drop on the ground. I even checked the catch can on the snorkel and not a drip. The oil just vanishes even while parked.
There are no performance issues. I get 23-28 mpg in the highway and 17 local; I get 15 mpg pulling a loaded two horse trailer local or highway. The oil loss always seems to occur when I am parked overnight and nearly only when I am parked over night. But never a speck of oil under the vehicle. I even sent the oil off for analysis and there is no dilution or significant contamination other than what would be normal - however, I had the mechanic who did the O ring and oil pump check everything and he is totally puzzled; I had a stealership check it out and they are puzzled and said they've never seen anything like it before. The only common conclusion is that the oil companies are selling Zero weight oil and labeling it 5W-30 and it's degrading and evaporation. No one can explain it.
Any thoughts on this one? Has anyone seen this type of thing before?
The issue: Intermittent oil loss of at least one quart of oil. I had the oil uptake O ring and oil pump on my Denali for the usual reasons. Now the problem is even worse and has become absolutely bizarre.
OK, so if I drive 1000 miles at highway speeds I don't lose a drop of oil, but it I drive locally, I'll lose a quart in 100 mile, but it occurs at random. I check the oil in the morning and evening to verify this all. I get up in the morning, the oil is at the full mark. I drive less than 50 to 100 miles locally, go home in the evening and the oil is exactly full. The next morning I check the oil and a quart has vanished. There is no oil on the ground in the garage, and absolutely no sign of a leak anywhere. But, sitting over night, a quart of oil has vanished. This will happen every two days just like clockwork. Every two days. Sometimes a quart of oil will vanish in a 20 mile trip, no smoke, no leaks, no nothing).
There is no smoke from the tailpipe at all at any load or speed (I had someone follow me to verify, and they observed no smoke at all even when a quart vanishes in a 20 mile trip, which is another issue). We checked all the seals, no leaks; We checked the compression, and it's exactly factory specs. The spark plugs have absolutely no deposits on them whatsoever. No oil contamination of coolant and vice versa. Where is the oil going and why?
I even hung a sheet under the chassis and drove and not a speck of oil, yet a quart vanished in as little as 10 miles. And this occurs at two day intervals like clockwork. I can check the oil and not drive the vehicle for two days and at two days, a quart vanishes with not a drop on the ground. I even checked the catch can on the snorkel and not a drip. The oil just vanishes even while parked.
There are no performance issues. I get 23-28 mpg in the highway and 17 local; I get 15 mpg pulling a loaded two horse trailer local or highway. The oil loss always seems to occur when I am parked overnight and nearly only when I am parked over night. But never a speck of oil under the vehicle. I even sent the oil off for analysis and there is no dilution or significant contamination other than what would be normal - however, I had the mechanic who did the O ring and oil pump check everything and he is totally puzzled; I had a stealership check it out and they are puzzled and said they've never seen anything like it before. The only common conclusion is that the oil companies are selling Zero weight oil and labeling it 5W-30 and it's degrading and evaporation. No one can explain it.
Any thoughts on this one? Has anyone seen this type of thing before?
