Oil change time interval

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Hi BITOG folks! I have an old high mileage back up car - Mustang 4.6*V8 that I do not drive much these days. How long can I keep the synthetic oil inside the engine before changing it? I do not drive much, but when I do, its all long highway trips... What is the best place for a buck to get a UOA that includes TBN? Thanks!
 
Oil change interval can vary based on the condition of the engine and if it's leaking oil. Most people here say 5k for conventional or semi-synthetic. And 10k for full synthetic. Age and mileage would also help. Older engines aren't as picky as modern gdi engines.
 
If you don't put more than 10k miles per year I'd say once a year with a quality synthetic like qsud or Castrol edge.
 
Originally Posted by Jetsfan421
If you don't put more than 10k miles per year I'd say once a year with a quality synthetic like qsud or Castrol edge.



...and if it's less than 5k per year, go 2 years. Mostly highway is easy on oil, as is the 4.6.

How many miles per year?
 
Originally Posted by ym42
Hi BITOG folks! I have an old high mileage back up car - Mustang 4.6*V8 that I do not drive much these days. How long can I keep the synthetic oil inside the engine before changing it? I do not drive much, but when I do, its all long highway trips... What is the best place for a buck to get a UOA that includes TBN? Thanks!


Three years easily.Even after this interval ,if you get a UOA you should get a result of a perfectly serviceable oil that you could use even longer.
 
Originally Posted by ym42
Hi BITOG folks! I have an old high mileage back up car - Mustang 4.6*V8 that I do not drive much these days. How long can I keep the synthetic oil inside the engine before changing it? I do not drive much, but when I do, its all long highway trips... What is the best place for a buck to get a UOA that includes TBN? Thanks!

If you care about the car do a UOA and be certain. I'm not a fan of blanket statements, they can get you in trouble. Check out Rock Auto for the Wix UOA kit, It is currently under $10 and includes TBN. If you can't locate it shoot me a PM and I'll send you a link.
 
My son goes once a year on his car that sits here in our driveway (doesn't want to take it to the apt complex). He drives it about 2K a year. When he drives it, he always goes 30 hwy miles at least and usually several hundred miles before stopping.

My Mom's '97 Buick goes about 3 miles twice a week. I change it every 6 months.

From what you are describing it would appear you could go a year between changes. demarpaint appears to have the best option for a UOA kit. I'd do one at 6 months and another at 1 year just for kicks and information.
 
I do 5k OCI's and have one vehicle that sometimes doesn't get 5k on it in a year. Personally, I change oil on a year or 5k interval, whichever comes first, when that is the case.
 
Hey OP,

I too have a high mileage 4.6 v8 mustang. Mine consumes about a quart every 3k Miles, and I use a high mileage oil (maxlife syn) which seems to help.

Mine gets driven a bit more than yours, but I only change the oil once a year with a quality synthetic.

You could probably stretch a quality synthetic two years if you wanted. I wouldn't worry about a UOA unless you just wanted one for giggles.
 
Originally Posted by ym42
Hi BITOG folks! I have an old high mileage back up car - Mustang 4.6*V8 that I do not drive much these days. How long can I keep the synthetic oil inside the engine before changing it? I do not drive much, but when I do, its all long highway trips... What is the best place for a buck to get a UOA that includes TBN? Thanks!


I have a similar situation with an older Porsche, I drove it around 4500 miles last year without changing the oil, and maybe 3000 or 4000 this year and plan to change it this Fall. It's a large sump at nearly 10 quarts and I use a high TBN oil, Mobil 1 0w-40 FS. Also, I usually drive it longer distances like a road trip here or there, but also some back country road cruising on some shorter runs.

I have confidence two years will be fine. I'm not going two years between changes to save money per se, I really believe two years is totally fine. It sounds like you're in a similar situation with your Mustang. And like you and others have mentioned, a UOA certainly wouldn't hurt for extra confidence.
 
A WIX UOA is around 15 bucks.
There are plenty of UOA results backing the "Oil can't tell time" statement, just search for UOA of 2+ years, there are some good ones.
 
I change at 5k on all my vehicles; on the truck and XTerra, it's possible that might go over a year. The only time I've ever changed based on time is the extreme example of my old Cavalier that sat in the yard unused for 3 years. I changed all fluids before driving it again, put 25k on it, and then got rid of it.
 
Originally Posted by Jetsfan421
If you don't put more than 10k miles per year I'd say once a year with a quality synthetic like qsud or Castrol edge.

Generally I agree with this statement. But since all the drives are long highway runs, you could easily get away with 18 month oil changes using synthetic. No problem.
 
First of all - thanks everyone for ya great replies!

BITOG got to be the BEST FORUM online as I had NEVER got so many replies in one day and this is awesome! Most replies were in line with what I expected and think myself.

To make this more fun for everyone I am going to share some more details here - this 06GT V8 with manual transmission only sees about 1500 a year - LOL! I do not quite remember when the oil had been changed last time but it has been about 3k miles since, and ( me thinks ) I have Mobil 1 0W-40 European formula in the pan:) The car does not burn much oil - I was adding about 1qrt /10k miles when it was my daily driver:) Thanks for the pointer regarding WIX UOA at rockauto, I was hesitating to spend extra $$$$ for TBN test at Blackstone Labs...

Now, my friends driving Hondas, and my Suzuki bike's manual calls for new oil filter every OTHER oil change. Without mentioning the time frame between changes. The filter I have on is K&N - whats the consensus on that? How often should I change the sucker?
 
No experience with K&N, but a filter will last just fine every other. Cellulose filters I'd not leave in too long with any kind of moisture build up, like a short tripper in FL. Before the Purolator fiasco, my dad cut his white cans open every time, and he kept them in at least every other 7.5k mi oci. No issues ever.
 
Originally Posted by Linctex
My 1997 Mustang GT 5-speed gets about 6,000 miles over three years. I change the oil every 3 years.


You can do anything you want. The Mustang went out of warranty a long, long time ago. Anything you do at this point is on your own dime anyway. I would be likely to do similar to some degree. For vehicles that are in warranty, not so much.
 
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