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Hey y'all! Long time no post

My 'Voy is modded including a muffler delete which (I'm guessing because of lack of back pressure) has made 4th gear completely useless. Man do I regret doing that but it does sound amazing. If I'm going under 85-90mph and it shifts to 4th I'll lose pretty much all power and it'll have to either unlock the TC or shift back to 3rd. So after a few annoying instances of it decelerating after shifting into OD I just started driving in 3rd all the time. It's been this way for over a year and I don't see really any negatives other than MPG and this. If the engine in 4th is spinning over 3000RPM which you'd have to be going about 100 it has the same power as 3rd. Anything under 3000RPM in 4th is useless.

Over the last couple long trips I've taken it on which are about 200-400 miles round trip because it'll be sitting at 3800-4000rpm the entire time the engine has decided to expand it's diet from fuel to oil as well. From what I can tell and some rough testing it appears this only happens when the engine is at high RPMs because for a couple of weeks I drove it only in the city and it used 0 oil then I took it to New Mexico and back over a weekend which totaled about 600 miles and it needed just over a quart after.

What would cause oil consumption only at high RPMs? The engine sings beautifully at that RPM and I haven't noticed any other strange noises from the engine like ticking or knocking. Only codes are for EVAP. The engine just rolled over to 250,000 miles and I get about 10MPG at 85 and 15MPG at 65.

I did a piston ring test I used on my Crown Victoria which was put it in 1st drive up to 5000-5500rpm stay there for 15 or so seconds then let off the gas and look to see if you got smoke, which I had none. The Crown does have bad valve seals so I got a badass James Bond smokescreen, poor 4.6 :( Only thing I get on the Voy is the occasional grey puff on a kickdown. Engine does need a valve cover gasket since plug #4 oiled itself pretty good about 8 months back, I've been putting it off but wouldn't this cause the same oil loss even at lower RPMs? Engine has no leaks I was just under there checking out the sway bar links.

Thank you!!
 
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