mustangspotential

Hey guys I've noticed recently my car has been eating a good amount of oil. Over the last 5-10k, I've had to add in between oil changes. When I bought it with 74k it didn't do this nearly as much.

Background: 06 GT 97k miles, not sure if spark plugs were ever changed as I bought it with 74k

Since I bought it I change every 7500 with Mobil 1 Full Syn HM and Motorcraft filter.

I've been adding a quart or so every month. Is this normal?

JCON

Do a compression test of the cylinders. This will help to pin point whether or no you have a bad seal or ring that is leaking oil. If you have one or more cylinders whose pressure is more than 10% lower than the highest tested pressure, add one oz of motor oil in to the cylinder via the sparkplug hole. Refit the compression tester and test again. If the pressure goes up, you have a stuck or failing piston ring. If it doesn't change, it is likely the valve guides/seals that need to be replaced.

If it is a failing piston ring, there are some things you can try first before tearing in to the motor. First, add 1qt of Marvel's Mystery Oil to your oil to top it off instead of regular oil. drive the car for 500-1000 miles and change your oil with regular synthetic, short change that around 3,000, if after testing your compression variance is under 10%, you can go to 5-6,000 miles but I wouldn't return to 7,500 changes for now.

The second part of the cleaning and probably what you should start with first is to buy 1 qt of ATF fluid. Take all your sparkplugs out and pour 2-3oz (I did 2 oz) in to each cylinder, place old towels over each cylinder head over the spark plug holes and turn the engine over for a few seconds (this will coat the walls of the cylinder with the ATF fluid), and then let sit for 24-48 hours. After that, put your plugs and coils back in and start up the car. It will smoke a lot and for 15-20 minutes so get it out of a garage and go drive it around. Once it stops smoking, I would let the car cool down and then later test compression again. The key is not so much the number's but the variances. A healthy engine should have less than 10% variance from the highest pressure to the lowest.

I had one cylinder test at 140PSI (and above average oil consumption) with the rest between 180-190PSI. I did the ATF trick and that cylinder went up to 165PSI (still too low). I did the Marvel's Mystery Oil for 500 miles and then changed oil, ran regular Mobile 1 synthetic for 3k and then changed (to get any other deposits out) and not 4 months later all cylinders are between 185-192PSI.

I was skeptical at first but at the idea of an engine rebuild due to a bad piston ring I was willing to try anything to get it back. The car runs better now than when I bought it 3 years ago. FYI its a 2005 GT with 70,500 on the clock.

algregory

JCON sounds very knowledgeable. I've been using "Tufoil" an additive and synthetic oils for a very long time. The following is from the Tufoil website.

Will using Tufoil help with an engine that burns oil?
Many old engines show signs of oil burning. Tufoil can help in some cases by freeing up partially sticking piston rings. There have been some dramatic improvements reported from the field where Tufoil freed up the rings and they started working properly again. However If the rings are cemented solid in their grooves or the cylinder is scored, no lubricant can eliminate the smoking.

Dino Dino Bambino

That shouldn't happen unless either the engine isn't run for long periods (e.g. car kept in storage), the engine is run only on short trips and doesn't have enough time to warm up, or if the oil isn't changed often enough.

JCON

I agree here. If you've been using it daily and allowing the engine to get up to operating temp every time you should be fine. I have seen some people use Tufoil but I have not personally.

BrianK

I park my 07 GT every winter in a heated garage. Mentioned above says I might expect cemented rings if the car is parked for extended periods - like winter storage. Do you guys have any suggestions on a recommended practice to store the car - maybe take plugs out and do the ATF thing to coat the cylinders?

JCON

I would think that, provided there aren't underlying issues, starting the car and letting it run for 10-15 minutes every 2-3 weeks would be more than sufficient. Might be worth doing the cleaning methods above just the ensure no (or a lot fewer) deposits or varnish remain during storage.

If you plan to park it for Six months, I would recommend adding Stabil to the fuel.

BrianK

I do add Stabil to the fuel and no fuel or rough running issues. Ok - an occasional start to keep the oil up and around the parts that need it.

jz78817

no, not really. idling for 10 minutes isn't a guarantee that the engine and all of its fluids come up to normal operating temperature. I don't drive my Mustang regularly during the winter, but as long as the roads are clear and dry (no snow or wet salt) I take it out at least every couple of weeks and go for a long cruise on the freeway.

Burning gasoline produces CO2 and H20 (water) which can recombine with each other to form carbonic acid, as well as forming nitric acid with the nitrogen in air. you really want to make sure you get your engine fully up to operating temperature for a while practically every time you start it. Otherwise it can't "burn off" the residual water, carbonic and nitric acids which will then collect in the engine oil and deplete the additives which contribute to the oil's total base number (TBN.)

if you're going to leave the car still for an extended period of time, it's far better to take it for a long drive, add stabilizer to the gas tank and top it off. then park it, let the engine cool, then after unplugging the fuel injectors pickle the engine with fogging oil and let it sit. might also want to put it up on jack stands to keep the tires from flat-spotting.

BrianK

Yeah you're right - no point in starting it up and getting all that moisture and other acids formed then shut if off. I did add Stabil and will call it a day (or a few months) and just leave it. Maybe take the plugs out and oil the cylinders a bit. And the jack stands are a good idea too. I do want to drain and fill the tranny oil also. I read in a Ford manual where they are starting to recommend a 3 part drain and fill (drain, fill and drive a bit - repeat 2 more times) as one method to swap tranny oil rather than a dealer flush. I have changed the filter last year but think that every fall I'll drain and refill and that should keep the tranny fluid clean. I also added a dipstick to make refilling much easier than that stupid snorkel in the pan. Also an oil change. Garage is heated so no real problem with moisture freezing etc.