Mileage vs. Time Question

Status
Not open for further replies.
Joined
Oct 27, 2016
Messages
4
Location
PA
black_beauty_2.jpg
I use a full synthetic (usually Castrol Syntec) oil in my 2010 Mustang GT Premium. The owner’s manual states to change the oil every 7,000 miles. Growing up my father & I restored multiple classic mustangs and we changed the oil every 3,000 or less, ritualistically. But my question isn’t about mileage, per se, it’s about mileage vs time. Even though she’s a “daily driver”, I rarely put more than 3,500 miles on her annually. So, should I replace the oil annually regardless if the mileage has not reached the recommended number of miles? She also sits sometimes days, in the garage, without even being driven while she stays hooked up to a charger/maintainer/desulfater, but I’ve recently been wondering about her oil changes. I live in Pittsburgh, PA if that might be a variable. Any advice and/or suggestions would be greatly appreciated. Thanks everyone!
 
Here's a data point you can use:

Car: Chevy Volt - An electric car, but it has an engine that goes along for the ride unless/until the battery runs down. Then the engine fires up.
Oil: Any Dexos1 5w-30 Oil

The car has an OLM.

There are two things that can consume oil life, and it appears that the OLM takes the worst of the two at any given time:
1) The mileage / use of the engine.
2) The time. For my car, the OLM makes you replace oil every 2 years, no matter how few miles you have on the oil.

I put about 1,000-1,500 miles on the engine per year (the rest is electric - engine is shut off), and it's clear that the OLM loses about 1% per week for 100% at 2 years.

Based on this (my best guess) if you're using a quality oil (dexos1 certification would be a plus to make it match my situation), you can probably go for 2 years on the oil.

Good Luck!
 
A lot of people will agree here on forum run UOA maybe half way in your normal interval at 6 month mark sense you said you run 3500 annually. I can almost promise you that UOA will come back perfect as long as you run the car 2hrs on highway before sample is taken.. I change my oil every 6k regardless of time and haven't had bad sample.
 
Hi,

I find that based on UOA that actual mileage and heavy loads, racing and lugging an engine wears it more and loads up the oil with wear metals, etc, driving down the Total Base Number of the oil and the Total Acid Number up.

Then I did a UOA of my sunday driver that I haven't used in 10 years, that oil still scored TBN of 5.6! with wear metals and water content that was so low it became clear that oil sitting in an engine for years, barring a coolant leak via the head gasket will still be OK.

With a late model Mustang and a newer, cleaner, tighter engine with much lower blow-by, you can do the Ford recommended intervals and longer once out of warranty, test the oil and see!

I now use 2 Filter Mags on the oil filter with 2" x 3/16" Sq neodynium bar magnets between the Filter Mags that visibly keeps the oil cleaner for up to 9-10 months and 8,000 miles before it even gets a little dark, never mind solid black!

If you can do any of that too, you got nothing to worry about!

 
You can do the UOA after 12-18 months and see where you stand. If it comes out good do the 2 years. If it were me I'd still change the oil annually as 3500 miles in one year is plenty of use on our toys. My car gets 1,000-1,200 miles per year and I'm still on annual oil changes despite all trips being 14-20 miles or more. I can do an oil change for under $20 with top synthetics and a Fram Ultra. $19 per year is not much of a concern. Until someone proves that a 2 year oil life is actually minimizing engine wear (and that's possible) I'll stick with annual. The concern there is that a new add pack every year could remove the current protective layer and reinitiate the same wear you were just protected from. In only 1,000 miles the protective chemical layer might not even be fully built yet.

Sitting for a few weeks or a month at a time makes no real difference in this decision. I know some guys with low mileage, 17 year old garage queens that only get driven 200-500 miles per year, and sit from Nov through early April without a start. The cars are still in perfect mechanical condition. Some of them are doing or considering 2 year oil changes.
 
I run two filter mags on my chevy L83 also it's best thing I've bought for my truck. Can't wait to get bypass filter setup.
 
Usually 1 of 2 options. Either 30-60 miles for 40-50 minutes one way then back or 5-10 miles for 15-20 minutes one way then back. Shorter times are side roads, etc... and longer drives are highways, turnpike, etc...
 
I've just traded in my Kia for a Suzuki.
I bought the Kia partly because of it's seven year warranty. However to maintain the warranty you need to get it serviced every year and in the UK, that can get expensive.
The Suzuki has a three year warranty so I plan to get the car dealer serviced after years 1 & 2. After that, I'll probably get it serviced every other year. I'll probably drive about 5,000 miles a year and the car's official OCI is 12,500 miles (using Petronas Synthium 7000 0W20) so I'll be fine.
 
With such low miles driven, your drivetrain warranty is for 6years from date of purchase.

Your IOLM will count down more based on time than miles and it will count down to zero based on a one year interval.

At the end of your 6 year warranty, you had better have proof of 6 oil changes should you need your warranty.

Do yearly changes until your warranty is up for sure (must be getting close).

After that.... Driven regularly, I'd probably continue yearly. But I've got some that haven't been changed in 3 since 300 miles would be a big year for that car.

Just another opinion
 
I have read many posts about this exact question. I even emailed Mobil and Chevron asking this question. And never have I heard what I consider to be a concrete explanation regarding the oil itself. Including from Mobil who said it was "a warrantee issue" and that "it's cheap insurance". (I think Chevron misunderstood the question so I gave up.) The most frequent explanation was probably just to get under there and check other things out. Which all I'm sure are true, but I would really like to hear a little more objective explanation regarding the oil. Not that I have any problem with changing oil. Frequently or not. $20 a year into a multi thousand dollar vehicle is inconsequential IMO. It's really just out of curiosity for me.

I have traditionally used M1 and changed every 7500 miles as recommended in the owners manuals for the new cars I bought. I never really paid much attention to the time intervals because they were never exceeded that I remember. Or at least I wouldn't have exceeded them by much. But I did the same 7500 OCI's for my occasionally and rarely driven trucks. Which amounted to every 5 years in my E350 that I made into a camper.

With both of the Ford vans that I own now, 1 year would be about 1000-2000 miles. Again, the money and the time to change the oil are inconsequential relative to a multi thousand dollar vehicle. But I really don't like the idea of wasting perfectly good synthetic oil either. FWIW, I never had a motor problem, even in the E350 that I changed only every five years. There's another guy on this forum that does the same. As I remember he also has a Ford truck.
 
Originally Posted By: OneEyeJack
UOA at 11 months and then decide. Good for records when you sell your current ride and buy your next Mustang.


That's a good point. While 2 yr oil changes might work for Bitog, the average guy out there is probably thinking 6-12 month oil changes. The next owner of your car might not be enthusiastic about oil changes >1 yr...unless you can show proof positive it was fine. And even then, what does Joe Schmoe know about TBN?
 
With a good syn I'd go at least 5,000 miles and push it to 18 months without sweating. Just make sure you get her heated up on a long highway run once a month or so...
 
In my experience, we need to worry more about oil leaks due to not driving the car.
I guess the seals are shrinking if they don't have any oil flow going through them.

I know this does not answer your question but OCI is actually not as important to preventing oil leaks.
 
It's not really about either miles or time - it's about heat cycles, fuel dilution, max op temp, humidity, etc. BUT, the MFG's try to make it simple and equate it to mileage and time.

You have a nice car. you need to get under, over, and around it thoroughly once a year anyway, so just change the oil while you're at it
smile.gif
 
Status
Not open for further replies.
Back
Top