looking at used cars to buy, i see occasional gaps in the oil change history that make me wonder. what percentage above the manufacturer recommended interval should be a concern when buying a used car? should I rule out a car if it missed a change altogether?
concerning oil change intervals.
- Thread starter BumperBozo
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Well if it’s a 3k interval and it went 6k it’s probably fine but there are too many variables we cannot see with driving habits that would determine that.
I used to do 3000K changes. Now they run between 4000 something and a high of 7154. I've done a few UOA and they have all came back just fine. My car is basically a sever service unit 80% in town. One or two major freeway trips a year. So I've stopped worrying about it no for the most part its just April and October OCI.
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That’s great to hear. I think I left a bit more ambiguity in my post than I should have, the driving habits of the previous owners of used cars are unknown so seeing a skipped oil change on a vehicle with a 10k interval would raise concern to me if it were a vehicle that was possible short tripped. That would be enough to rule a vehicle out to me. I am basically just listing the two extremes here but it’s all up to the buyers judgement. I personally run whatever synblend is on sale for 5k and it stays relatively amber and clean, although that isn’t the main determinant as to whether it’s still good or not.
In this day and age of Carfax reports that list vehicles with "regular oil changes" and other services, I think with some effort you can find a used car that's been well maintained, instead of taking a chance on one with an incomplete history. Then if you're lucky enough to find a vehicle owned by one of us obsessive compulsive nuts, that's even better.
Welcome to BITOG 
That is only one part of the picture you look at when inspecting the car. Not all places report to Carfax, particularly the smaller shops.
Look under the oil cap, does it look clean? If the filter is up top, what is the date code on it?
It's possible that the car got its first oil change or two from the dealer since they're often free, but will have no service records even if it was regularly serviced a smaller shop since they might not furnish them.
That is only one part of the picture you look at when inspecting the car. Not all places report to Carfax, particularly the smaller shops.
Look under the oil cap, does it look clean? If the filter is up top, what is the date code on it?
It's possible that the car got its first oil change or two from the dealer since they're often free, but will have no service records even if it was regularly serviced a smaller shop since they might not furnish them.
Vehicles with good regular carfax reports are out there if you look for a little while. Often they are at the same dealer who did the oil changes because they were a lease vehicle. So you pay a little more to buy a used car from a dealer. Though some have a certified used rating that means the dealer did go over the vehicle and service anything due, and usually dealers include a one year warranty, so there is that.
Over the years I have seen many vehicles with destroyed engines because someone ran them until they ran out of oil and then continued to run them until they would not run anymore. There are many people who do not have the first clue about what makes a vehicle move, and what is required to keep it in proper condition and not damage the engine. Believe me they are out there. Ask any mechanic, they have seen the vehicles with engines that are damaged by not changing the oil.
Over the years I have seen many vehicles with destroyed engines because someone ran them until they ran out of oil and then continued to run them until they would not run anymore. There are many people who do not have the first clue about what makes a vehicle move, and what is required to keep it in proper condition and not damage the engine. Believe me they are out there. Ask any mechanic, they have seen the vehicles with engines that are damaged by not changing the oil.
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One time bought a used car from a dealer, Carfax and all. Then I learned that motor oil was getting into the cooling system. After that hassle I went in to a non-dealer to get a wheel alignment. I was told that the car had been too heavily damaged to get the wheels into alignment specifications. This was with Carfax and all.
When I bought the 4Runner it was 17 years old. CarFax showed about 7 oil changes. Careful scrutiny (I spent about 2 hours looking over the car (private party)) I was able to determine how it was cared for. It was a solid car that needed some consumables but I didn't care. It cost me less than half what other 4Runners were going for.
"Do Your Homework"
"Do Your Homework"
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I do ALL my own maintenance and maintain an Excel spreadsheet. You won't find any evidence of my vehicle maintenance anywhere except my own records. My vehicles are NOT for sale. Yes, they are too old and high mileage to be "worth anything." They are also completely paid for and completely reliable. Everything works on my go to work 17 yr. old go to work beater; the A/C and the heated seats. A new vehicle (which I can write a good check for) is a depreciating asset/liability. My "car payments" are in the bank. Guess what? There's a lot of guys out there like me. 
I've got a '97 Ford Escort wagon with 41K miles on it. It's been garaged and when it's clean it still looks nearly as good as the day I drove it off the dealership lot and still drives just as good as the day I bought it new. I can't remember any instances where it might have had something done that would show up on a Carfax because in the past I've done my own repairs/maintenance. I'm not even sure anything would show up on the Carfax other than where it was titled in NC when I bought it new and when I transferred the title to KY when we moved 10 years ago. All I can say is someone would miss out on a very good car if I were selling it and they wouldn't buy it because of lack of a complete Carfax. I have 99.9% confidence in it's reliability and it's usually the car I drive when going on highway trips. Actually, I suspect well over 75% of the miles on it are easy highway miles. I've bought several used cars over the past 40 years. I've never checked the Carfax on one prior to purchase. I just look them over, drive them to see how they drive and whether there are any unusual noises, listen to the way they run/how the transmission shifts, check fluids etc. and use my own judgement. Thus far I haven't been burned on one using my own judgement. I keep a notebook on my '16 Versa with date/mileage/cost of everything I do to right down to filling it with gas but I don't bother keeping receipts. Yes, it's a record but an unverifiable one. Personally, I bet manufacturers figure in at least a 25% buffer on oil change intervals.
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I'm like you. Excel spreadsheets for all three cars. Two are a page and half each. Any future private buyer should be satisfied, since Carfax histories sometimes only tell "part of the story." I have had good luck selling vehicles either to people I know or to buyers on Autotrader. I will always pay more for a used vehicle with a documented maintenance record, even though some people don't care.I do ALL my own maintenance and maintain an Excel spreadsheet. You won't find any evidence of my vehicle maintenance anywhere except my own records. My vehicles are NOT for sale. Yes, they are too old and high mileage to be "worth anything." They are also completely paid for and completely reliable. Everything works on my go to work 17 yr. old go to work beater; the A/C and the heated seats. A new vehicle (which I can write a good check for) is a depreciating asset/liability. My "car payments" are in the bank. Guess what? There's a lot of guys out there like me.
That's true indeed ^^^^^^^^^^^^^
And quite funny in a way.
I was fortunate to get my car with 39,990 miles and it had someone who maintained the car very well.
Probably part of the reason why I am now over 330,000 miles now and counting.
I've bought at least 2 cars with missing OCIs in their CARFAX and had very good luck with them because I can sense when a car has been well maintained by 1 or 2 owners. With many more owners than 2, it gets much more risky.
Many oil change places don't seem to record an OCI with CARFAX, so it seems likely that OCIs was never missed with many cars.
Many oil change places don't seem to record an OCI with CARFAX, so it seems likely that OCIs was never missed with many cars.
CARFAX can be a pain to deal with. When I had my AC serviced at a private car repair place, they entered the wrong current mileage so I contacted CARFAX to get it fixed and I didn't think they ever did so.
I've done my own OCIs for about 30 years and I still do, plus air filters, cabin filters, coolant flush, etc.
All these things will never reach the CARFAX on my car b/c I know what a pain in the neck it would be to deal with CARFAX.
But I'm one of the 1% of car owners who babies my car like it's a new $100,000 Porsche, even though it's 9 years old and has 112k miles on it.
I've done my own OCIs for about 30 years and I still do, plus air filters, cabin filters, coolant flush, etc.
All these things will never reach the CARFAX on my car b/c I know what a pain in the neck it would be to deal with CARFAX.
But I'm one of the 1% of car owners who babies my car like it's a new $100,000 Porsche, even though it's 9 years old and has 112k miles on it.
Run a Carfax on my cars. You won't see a single oil change.
Consider that the owner decided to try it himself, didn't like it, and resumed his visits to Jiffy Lube.
Consider that the owner decided to try it himself, didn't like it, and resumed his visits to Jiffy Lube.
Just because a service wasn't recorded doesn't mean it was not done. There are lots of dealerships that don't even update their own brand's official website / vehicle history (by VIN) with service records. You just don't know. Of course all else being equal, I would choose a vehicle with no gaps in its service history. But bottom line, if you find a car that seems good and you like what you see, have a PPI done at an independent shop.
Don’t trust the whole “well maintained vehicle” or “regular oil changes” tags on Carfax, it is a flawed system. Because I DIY all my oil changes, my Ford had zero oil changes on record in 88K miles but because it was so unreliable and was in the shop for other repairs so often, Carfax labeled it both “Well maintained.” and “Regular oil changes.” when it was listed for sale on the used market.
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