I noticed everyone always goes by the mileage interval but never specify on how many months, why is that? on the subject I have an 02 Mustang GT w/ 7k miles, had it since new. did the 1st oil change at 500 miles w/ 5w20 MC and changed it again at 1K w/ Amsoil 5w30, changed the oil yearly since then and the filter (SDF) every 6 months...Should I still change my oil yearly regardless of the low miles I driven it? I just did an oil change before I found this site, so I never thought about UOA, But will be getting one next time. Thanks for any input
OCI on a seldom driven mustang
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Why do people not follow 'month' intervals? Because there is very little evidence here to date that anything bad intrinsically happens to oil if it is just left sitting in an engine for a reasonable length of time.
The 3 month (or 6 months or 1 year) interval is derived from the assumption that a car very seldomly driven in 3 months will experience quite a bit in terms of very short trips, ie: maybe 5 trips a day, of 2 or 3 km duration. This would have covered an individual such as my grandfather, who drove his car approximately 4000 km per year, yet went through a good half dozen mufflers in the 15 years he owned his car.
However, if the car just isn't driven at all, and assuming its not stored in a seriously moist/damp condition, theres no reason why the oil shouldn't last in the crankcase indefinitely.
Personally, if I were you, I wouldn't bother with the filter change at 6 months. Change the oil once a year or once every two years, and no need to use expensive Amsoil when the MC 5W-20 is a very appropriate oil and a lot cheaper to boot.
The 3 month (or 6 months or 1 year) interval is derived from the assumption that a car very seldomly driven in 3 months will experience quite a bit in terms of very short trips, ie: maybe 5 trips a day, of 2 or 3 km duration. This would have covered an individual such as my grandfather, who drove his car approximately 4000 km per year, yet went through a good half dozen mufflers in the 15 years he owned his car.
However, if the car just isn't driven at all, and assuming its not stored in a seriously moist/damp condition, theres no reason why the oil shouldn't last in the crankcase indefinitely.
Personally, if I were you, I wouldn't bother with the filter change at 6 months. Change the oil once a year or once every two years, and no need to use expensive Amsoil when the MC 5W-20 is a very appropriate oil and a lot cheaper to boot.
I've got a '55 Austin-Healey that doesn't see much use each year (less than probably 500 miles depending on the year and how much time I have to drive it.) I've been changing it every year with dino 10w-40. I've thought about still changing each year with some $.88 Walmart Supertech oil or perhaps changing every two years and use a HDEO 15w40 like Rotella. What makes the most sense?
I wonder if this is a case where an ester fortified oil like Castrol Startup (or just pouring several ounces of Redline Oil in) would help. Since the esters make a molecule thick coating that more or less adheres to the metal, maybe it would also help prevent corrosion from sitting all that while.
I have a Mustang that's driven a similar amount. It spends most of it's time sitting but when it is driven it's usually taken on a trip.
It was recommended to me that I pull a sample once a year and get a UOA done but don't change the oil unless the sample showed it needed changed...
It was recommended to me that I pull a sample once a year and get a UOA done but don't change the oil unless the sample showed it needed changed...
I agree with jsharp.
You really don't know without analysis.
What worries me with my seldom used F-150 is the accumulation of water and unburned fuel in the crankcase.
You really don't know without analysis.
What worries me with my seldom used F-150 is the accumulation of water and unburned fuel in the crankcase.
Or it could make the problem worse as esters are often hygroscopic.
Read some of Molakule's comments; some ester-based refrigeration and jet engine oils can exceed their maximum permitted concentrations of water with just minutes of exposure to air.
Another thing -- if engine components were prone to corrosion or rusting, just the mere operation of the engine itself would cause significant corrosion. After all, the rate of a chemical reaction such as corrosion increases exponentially as a function of temperature (see: Arrhenius equation), and a 200degF engine would see more corrosion than an engine stored at a more normal ambient temperature.
I left M1 5w30 in my Mustang under these circumstances for 22 months through 2 Illinois winters. I did a UOA and the iron might have been a little high but everything else looked normal. Hard to say since it was the first UOA I'd done on it.
It showed no excess fuel, no excess moisture.
But as I said, when the car is used it's used for trips of a couple of hours minimum so that might be a factor...
Patman
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I have a friend who has a 97 Cobra who only drives it about 3000 miles a year, and he did the same thing with the 96 Mustang GT he had before that. He only ends up changing his oil about once every 18-24 months. When he does drive the car, he always gets the engine good and hot, as he takes longer trips. I tried to get him to do a UOA on his last Mustang before he sold it and bought the Cobra (he bought the 97 Cobra used about 1.5 to two years ago), but he didn't get around to it. It would've been interesting data.
I look at it this way. A seldom driven car is NEVER going to wear out it's engine. For example, if you do 3000 miles per year with a car, and own it for 30 years, you'll still only have 90k on it. Even if you only changed your oil once every 2 years, I'd be willing to bet the engine would still make it to 90k without a problem at all (as long as everytime you do drive this car, you get the oil up to full operating temperature long enough to remove the moisture)
I look at it this way. A seldom driven car is NEVER going to wear out it's engine. For example, if you do 3000 miles per year with a car, and own it for 30 years, you'll still only have 90k on it. Even if you only changed your oil once every 2 years, I'd be willing to bet the engine would still make it to 90k without a problem at all (as long as everytime you do drive this car, you get the oil up to full operating temperature long enough to remove the moisture)
Red Line 5W30 every 5000 miles, or 1 year.
I garaged my 03 GT after my rear-end install.
I garaged my 03 GT after my rear-end install.
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