Synthetic oil truths

I have just read a lot of opinions about long-life synthetic oils and long-life filters. Fram has an UltraGuard that they say good for 20,000 miles.
Does anybody have any actual references to say that the mileage quotes are valid?..or, references to say they are hype.
I am looking for data, not anecdotes. With three cars from 13 to 26 years old, I have a whole lot of my own anecdotes.

My vision of Hell: being sent to a room of folks discussing oil life…for all eternity :grimacing:


Great way to start an argument, discuss sex, religion, politics or oil life


Head on over to the web forum This is an endless forum of thousands who discuss oil issues.


What does your owner’s manual say?

What does your owner’s manual say?

Basically if you use an oil and filter that meets your car’s manufacturer’s specs, and abide by the mileage and elapsed time between oil changes per the manufacturer’s schedule, then you’re fine. With that said, some people (myself included) have brand preferences based on (but not limited to) experience, specs, heresy, or OCD.

A lot of it is just advertising fluff. I know many people who buy the most expensive oils and the most expensive filters and do oil changes every 3k miles…and then sell their vehicle after 3-4 years of use.

As an old time participant use to say…"Are you trying to get the most out of your oil and filter, or the most out of your car?

Read the owners manual. Don’t exceed its recommendations.

If it is older cars then that is your call . If it is still under warranty most now will say follow the oil life monitor or once a year . Doesnt matter what oil filter makers or oil producers say if you have to follow auto makers warranty specs .

I would consider long oil change intervals only if I were driving almost exclusively on the highway.

Good luck finding data that’s relevant to your particular driving conditions.
You could periodically get your oil analyzed, but for most non-commercial cases it doesn’t make sense spending as much on analysis as just getting an oil change.

Real data from real analysis.


Tester comes through again with just what I am looking for!

From the report;

“Those 5,234 reports are associated with oil samples that, on average, were used in the engine for 3,900 miles before draining.”

When changing the oil that frequently, the study of the benefit of better engine oil is pointless. The vehicles that I work on daily receive oil changes 10,000 to 12,000 miles with quality Exxon-Mobil synthetic engine oil with no sludge or engine problems.


It surprises me that people that use the more expensive oils don’t seem to leave them in the engine significantly longer than the other oils/ I would like to see data on the store brands but I guess that people that buy store brand oil are not likely to send it in for analysis.

I find it interesting that Toyota did not change yheir filter when they changed to synthetic oil. I also think long life filters are probably a waste of money.

Another curiosity, 5 quart jugs of full synthetic costs only $5 to $7 more than conventional oil. Why are most places charging double or more for a synthetic oil change.

We’ll just agree to disagree. I only use Mobil. I used to use Pennz in the first half of my life but now just Mobil. I really don’t care about the cost, it just makes me feel better. I change the syn at 5000 and the dino at 3000. My FIL was a farmer and I helped him change oil once. I was in horror when he dipped his finger in “used” oil to lube the filter gasket. I only use new oil on the filter gasket. Yes I understand it is over the top but that’s the way I do it. I don’t really care what Bob says.

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Oil life is largely governed by the environment it sees and the amount of buffers it contains. Mobil 1 Extended Life is the only Mobil 1 product that has the extra buffering compounds to keep their product stable for more than the manufacturer’s recommended interval. If the oil manufacturer doesn’t tell you their product has extra chemicals to extend life, it probably doesn’t. California did an experiment on state motor oool vehicles from cars through their big trucks. They found that the large trucks and buses can go tens of thousands of miles between changes, largely due to the huge oil sumps. Their cars were good through 10,000 miles, IIRC. I’ll see if I can find the report.

I have to disagree with that. It has more to do with perceived ownership cost. If it was government mandated then I’d expect to see it mandated in every manufacturer. My 14 Highlander has a recommended oil change of 10k miles. My sons 2017 Hyundai has an oil change recommendation of 5k miles (full synthetic). My friends 2017 Corvette has an oil change recommendation of 5k miles (full synthetic).

Most of that will be going away in 10-20 years as manufacturers switch over to fully electric vehicles.

It is because they didn’t NEED to change it. No “special” oil filter is required for synthetics.

Because people are willing to pay more for that. The price of anything is not a reflection of the cost. Unless, of course, the cost is higher than the price.


Nobody said anything about being “government mandated”

You’re right…I read it too fast. That’s what I get when I try to multitask. I’m proof reading a new clients technical proposal. Took a break for a few minutes.

I use the manufacturer’s recommended oil change interval, and have for almost 50 years, without problems. These days, it means using the OLM. The comment mostly addressed testing to determine oil change intervals. California did a well controlled study where they tested the oil periodically and only changed when the oil analysis said it was time.

Just keep in mind the driving conditions of those California fleet vehicles may be very different than those of a private car owner.
My last oil interval, with synthetic, was 3500 miles over 14 months.