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Hello everyone,
I've recently bought a used 2011 with 63k miles on it and out of nowhere I decided to check the oil and noticed I was low so I filled it back up to the top and kept driving. After 1k miles I checked again and saw that I was 2 quarts low, I know these cars burn oil but not this much. It has a catch can, and it only fills up about 1/6 to the top in about 1k miles and I checked behind the TB and there is no oil there either. Even when I full throttle it there is no smoke from the exhaust and I don't smell any oil being burned if it were to be leaking from the valve cover. I am getting pretty stumped as to what would be the problem I am having. Does anyone have anyone have any tips on what could be wrong?
 

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Think I'd have a compression test done on the cylinders, sounds like you may have some bad rings. Only time I have to add oil is when I change it out and I run the hell out of my engine......:oops:
 

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2qts in 1K miles is a lot. Mustangs if beaten on and driven hard regularly are known to burn oil, but not this much. I would say it should burn no more than 1qt per 5K oil change and anything more than that is room for concern. As recommended a compression test is a good start. Also does the coolant look normal color and consistency?
 
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Discussion Starter #4
Think I'd have a compression test done on the cylinders, sounds like you may have some bad rings. Only time I have to add oil is when I change it out and I run the hell out of my engine......:oops:
I just ran a compression test on all the cylinders and they were all between 165 PSI and 180ish but if it was a blown oil ring the compression wouldn't change if I'm not mistaken? The coolant also looks fine, it is still a translucent red orange with no bad smell or discoloration
 

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I just ran a compression test on all the cylinders and they were all between 165 PSI and 180ish but if it was a blown oil ring the compression wouldn't change if I'm not mistaken? The coolant also looks fine, it is still a translucent red orange with no bad smell or discoloration
Hmm, I believe you want to be within a 10% difference between cylinder psi's and yours appear to be a bit low, think you should be seeing closer to 190 psi, Beechkid would know better. Another thought. Most engines have a separate oil control ring. If that was bad, but the compression ring was good, you might still get good compression, but have oil passing by the rings. Have you removed the spark plugs? Oil consumption of that magnitude will certainly show on the plugs.
 

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Hmm, I believe you want to be within a 10% difference between cylinder psi's and yours appear to be a bit low, think you should be seeing closer to 190 psi, Beechkid would know better. Another thought. Most engines have a separate oil control ring. If that was bad, but the compression ring was good, you might still get good compression, but have oil passing by the rings. Have you removed the spark plugs? Oil consumption of that magnitude will certainly show on the plugs.
I went and labeled all the plugs and figured out that the darker plugs are actually the one with the higher compressions. It looks more like they are carbon fouled than burning oil. I attached the spark plugs showing 1-4 being on the passenger side from the radiator to the firewall and 5-8 on the drivers side from the radiator to the firewall.
 

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When you did the compression check, did you do both wet & dry? In general, 1st you do dry to check for the 10% differentiation then you add a teaspoon of oil to the cylinder and check again....if the psi goes up on that cylinder (10% or more), the oil rings are worn. Although I did not go online and dig up the specs for the specific minimum psi spec, what you have all seems very good to me..... IMHO I would look at doing the wet test and then the cylinders that had the carbon buildup on the plugs, I would look at the possible valve related issue...could be something as easy as a couple of valve guide that are worn... fairly easy fix!!!! IMHO, I think you are overall in good shape!
 

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When you did the compression check, did you do both wet & dry? In general, 1st you do dry to check for the 10% differentiation then you add a teaspoon of oil to the cylinder and check again....if the psi goes up on that cylinder (10% or more), the oil rings are worn. Although I did not go online and dig up the specs for the specific minimum psi spec, what you have all seems very good to me..... IMHO I would look at doing the wet test and then the cylinders that had the carbon buildup on the plugs, I would look at the possible valve related issue...could be something as easy as a couple of valve guide that are worn... fairly easy fix!!!! IMHO, I think you are overall in good shape!
I did the compression check with the dry method. I haven't tried the wet compression test yet so ill try and do it tomorrow and see if the specs are 卤 the 10%. I hope it's nothing bad, since I just bought the car 5 months ago
 

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I finally got around to doing a dry compression and then directly afterwards I ran a wet compression test only using like a tablespoon of oil, the compression only went up between 1% to about 5% on different cylinders so it seems like everything is fine interms of seeing a spike of 10% or more which rules the piston rings and walls out from being bad, im pretty sure. Does anyone have any more ideas or tests I can run to rule out more stuff?
 

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I finally got around to doing a dry compression and then directly afterwards I ran a wet compression test only using like a tablespoon of oil, the compression only went up between 1% to about 5% on different cylinders so it seems like everything is fine interms of seeing a spike of 10% or more which rules the piston rings and walls out from being bad, im pretty sure. Does anyone have any more ideas or tests I can run to rule out more stuff?
How hard do you drive your car on average? You doing a lot of WOT and sporty driving or not so much?
 
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I finally got around to doing a dry compression and then directly afterwards I ran a wet compression test only using like a tablespoon of oil, the compression only went up between 1% to about 5% on different cylinders so it seems like everything is fine interms of seeing a spike of 10% or more which rules the piston rings and walls out from being bad, im pretty sure. Does anyone have any more ideas or tests I can run to rule out more stuff?
A leak down test will also tell you about any valve leakage, though I鈥檓 not sure a valve leak would cause excess oil consumption.


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A leak down test will also tell you about any valve leakage, though I鈥檓 not sure a valve leak would cause excess oil consumption.


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I don't think a bad valve seal would be the cause of burning 2 quarts every 1k miles, I was looking for leakdown testers at Harbor Freight, i'll only be using it once since thats the average lifespan of a harbor fright tool
 

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I do a lot of WOT not gonna lie, I have a really heavy right foot :)
Honestly this could be the cause. Don't ask me why as I have no idea the technical terms, but had this issue with one of my 2006 4.6L real bad. Not quite as bad as you are describing, but about 1 to sometimes 1.5 QTS every 5K miles... Got a oil catch can and would catch some in there and empty into a bottle to track how much, but never got the full amount missing so no idea where the rest was going... Seemed the harder I drove it the more went missing. Took it relatively easy for 3-5K miles and not much went missing and went back to getting it WOT a lot and back to missing. Had a much more mild issue like this with my 2011 GT as well. My Boss 302 I don't recall it being to bad as I never needed to add oil in between changes, but it would eat a little to say maybe the 1/2 mark on the dip stick so what 1/2 qt or so between changes so not bad, but most my Mustangs consumed a little oil here and there and more the harder they were driven.
 
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Don't ask me why as I have no idea the technical terms
Blowby increases greatly at WOT. Increased oil consumption under these conditions is pretty normal, but OP鈥檚 is still very high. I couldn鈥檛 burn that much oil if I tried. The condition is also exasperated greatly on supercharged engines.

Got a oil catch can and would catch some in there and empty into a bottle to track how much, but never got the full amount missing so no idea where the rest was going...
The catch can helps, but can鈥檛 capture it all. There are some very high-end, custom, multi- catch-can configurations that allegedly get closer to the mark. I鈥檝e seen them at the track, but haven鈥檛 seen them for sale.

The better your rings seal, the less of an issue you鈥檒l have with this.

You should always check, and top-up your crankcase before/after high-performance (WOT) runs, and don鈥檛 be surprised that you have to add a little now and then.
 

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Blowby increases greatly at WOT. Increased oil consumption under these conditions is pretty normal, but OP鈥檚 is still very high. I couldn鈥檛 burn that much oil if I tried. The condition is also exasperated greatly on supercharged engines.



The catch can helps, but can鈥檛 capture it all. There are some very high-end, custom, multi- catch-can configurations that allegedly get closer to the mark. I鈥檝e seen them at the track, but haven鈥檛 seen them for sale.

The better your rings seal, the less of an issue you鈥檒l have with this.

You should always check, and top-up your crankcase before/after high-performance (WOT) runs, and don鈥檛 be surprised that you have to add a little now and then.
If my catch can was filling up I would know what the exact problem is and like you said catch cans are not 100% efficient but they still do their job. I'm starting to get more and more confused since I took it out the other day and did a couple WOT pulls and I saw no smoke in the mirrors and then I let it sit at high rpms down a hill and gassed it and I think I saw a little smoke but I think it was just my imagination desperately try to see a problem. I'm going to go call around and see if a shop can fix the problem I'm having since its getting a little worse every time I drive it. I was just recently thinking that if I didn't fill it between an average 5k mile oil change my car will burn 10 quarts lmao which is kinda impossible
 

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I don鈥檛 remember if you stated the oil you are using or not, but most synthetic oil doesn鈥檛 produce much (if any) smoke.
 
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A leak down test will also tell you about any valve leakage, though I鈥檓 not sure a valve leak would cause excess oil consumption.
A cylinder leak-down test will tell you about pressure leakage past the compression rings and at the valve seats, to help identify the sources of low compression. Anywhere pressure can leak from the cylinders.

It won鈥檛 help you find leaking valve-stem seals, or worn valve guides, or damaged oil rings, where oil consumption can also be an issue.
 

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If my catch can was filling up I would know what the exact problem is and like you said catch cans are not 100% efficient but they still do their job. I'm starting to get more and more confused since I took it out the other day and did a couple WOT pulls and I saw no smoke in the mirrors and then I let it sit at high rpms down a hill and gassed it and I think I saw a little smoke but I think it was just my imagination desperately try to see a problem. I'm going to go call around and see if a shop can fix the problem I'm having since its getting a little worse every time I drive it. I was just recently thinking that if I didn't fill it between an average 5k mile oil change my car will burn 10 quarts lmao which is kinda impossible
What brand and viscosity oil are you using?

Also you likely won't see smoke as it isn't burning much off each time just it all adds up over each drive/time...
 
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