Burning oil at high speeds

OK. Did compression test today finally. First compression tester didn't have long enough threads so had to go get another one at the local auto parts store. Luckily I have more than one car. Anyways, that doesn't seem to be the issue. Here's my results:
654321
155170175170165160
155165180175175155
So I didn't believe the results since they were so much higher than 150 and I tried the other tester (with threads from tester 2) on cylinder 1 and got 170. So they seem to be correct, or at least in the ballpark.

I don't know what the problem is now. I really thought it was going to be rings.

I changed the oil and put in high mileage conventional 10w30 (was full synthetic) and will see if that makes any difference, I guess. Will post next time I take it for a long drive and see how much it burns.
 
That is a dynamic compression test, try a leak down test, then listen to where you hear the air is coming out of. Exhaust pipe is an exhaust valve leak, throttle body is an intake and oil fill port is rings.
 
Those compression numbers are within the specs in my factory service manual. I really don't think it is rings, something else is going on. If you had bad rings you would burn oil, but at a much slower rate. I've seen 4.0's with bad rings and valve seals, so bad that they blew a puff of blue smoke while they accelerated, and they still didn't burn oil at this rate. Since it has something to do with highway driving, it sounds to me like there is something up with the PCV system. The oil is going somewhere. If you don't have any significant leaks I'd be pulling the valve cover and intake manifold along with the PCV hoses. How does the air intake tube look?
 
The oil is going somewhere. Agreed! I did replace the PCV intake elbow. Air intake tube looks clear and clean.
I am thinking next step is to do the leakdown test. I see directions online for just putting in the air and listening, whereas other directions include a leakdown tester that measure % loss - is the tester needed? Planning to do that next weekend.
 
twotrack said:
The oil is going somewhere. Agreed! I did replace the PCV intake elbow. Air intake tube looks clear and clean.
I am thinking next step is to do the leakdown test. I see directions online for just putting in the air and listening, whereas other directions include a leakdown tester that measure % loss - is the tester needed? Planning to do that next weekend.
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The testers with the gauge are handy, it’ll give you a real reading of how much pressure each cylinder can maintain
 
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I'm wondering, also, since "the oil is going somewhere" if it would be worth trying the dyed oil and black light (from the service manual) to check for leaks after driving it around at 75mph for a while.
 
OK. So I put in the dye, drove it 300 miles, probably 150 of which was at 70mph+. Went through 2 quarts of oil. Crawled underneath with the blacklight and voila! Oil all over the air conditioning compressor. But, where is it coming from I don't know. Any ideas appreciated. Looks like it may be worst at the top of it and dripping around but hard to tell. Sorry for the crappy pictures. FYI, I've never seen any drips in the garage. I'm assuming it mainly loses it on the highway and then gets coated with dirt.
top_compressor_oil_try2.jpg

bottom_compressor.jpg
bottom_compressor_oil.jpg
 
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