Should I use synthetic motor oil on 2010 Odyssey/2001 F150

[Indywar2]

Good morning,

I am hoping the forum can help clarify when should a vehicle be switched to synthetic, and when does it provide more risk than benefit.

I have two older vehicles (2010 Honda Odyssey and 2001 F150) that I have used Quaker state high mileage motor oil for years.

I have read that switching to synthetic in older vehicles (no one defines "older") could cause seals, etc to leak with synthetic more than with dino oil. I suspect this may depend on the vehicle/engine but have no idea. As I change my own oil, changing it less often is not a major consideration/benefit to justify the higher synthetic costs either.

I would appreciate any opinions if switching my two vehicles (or just one) to synthetic makes sense, and why.

Thanks,
Rob

 

[JayhawkRoy]

If you're happy with the QS high mileage oil, I would continue with it. It appears to be a syn blend anyway, so I am not sure what you would gain with a full synthetic, and the extra cost that goes with it.

 

[CT8]

What makes you all of a sudden want to try syn oil? Will syn oil cause a leak who knows and most of the stuff on the internet is B.S or regurgitated info by people that are not qualified. Most oil companies have 1 800 phone numbers call several and ask them. Report back..

 

[mclasser]

How many miles on the cars? What are you trying to achieve with syn oil?

Syn oil doesn't cause leaks. The uniform molecular makeup can slip past/clean up worn areas and, in-turn, expose leaks/increase consumption.

 

[oil_film_movies]

The old tale of "syn oil causes leaks in older cars" actually may have some truth to it. ::::: A Valvoline engineering tech rep discussed it one time with a company engineer present in https://www.youtube.com/watch?v=FXqkOZAkXZw at the 26:00 point in the video especially. They talk about gunk around the seals (from normal old oil in an old engine) actually helping to keep the seal working. Then, a synthetic might clean out the gunk, causing a leak. .... I think it doesn't always happen, but it could. For the old F150 here, just use the cheapest SuperTech conventional from Walmart. The newer Honda can probably easily switch to a High Mileage Full Synthetic, recommending Valvoline HM full syn, or really any HM full syn should be fine.

 

[y_p_w]

The whole idea of "synthetic oil causes leaks" is ancient and generally doesn't apply to most current motor oils nor current seal materials. Several 2010 Honda vehicles specified 0W-20 (which by definition is a "synthetic oil") and Honda has specifically stated that a 0W-20 is acceptable for a 2010 Odyssey.

The old issue was compatibility with PAO, which tended to harden and shrink seal materials - especially if they were aged. The oils were formulated with other ingredients to counter it, such as ester base oils and seal swell agents, but the PAO could harden it first before those other components caused the seals to soften. Some found that they would leak initially but then stop leaking.

Quote
https://www.lelubricants.com/lit/news/White Papers/when_do_synthetic_lub.pdf
Polyalphaolefin (PAO) Disadvantages Additive solubility limited, some seal shrinkage

Because of the varying functional groups attached to the ester group in the ester molecular structure, some esters are used along with very nonpolar fluids, such as PAOs and chemically modified mineral oils, to improve the solubility of polar additives. Also, certain esters have been found to promote slight seal swelling; thus, they can be used as additives to lubricant base fluids that cause seal hardening to offset the hardening affect.

I heard that part of the reason why PAOs aren't as common is because modern Group III base oils have better compatibility with seals, but also they're less expensive. The definition of "synthetic oil" has changed a lot over the years. These days it's probably more about performance level than it is about the specific type of base oil that's used. Pretty much any new motor oil meeting API SN specifications is going to have some sort of synthesized base oil, whether or not it's marketed as "conventional" or "synthetic".

 

[Hall]

Keep using what you're using. It seems to be working fine.

 

[dave1251]

There is no reason to change what you are doing. You will not have an oil related failure with your current maintenance practices.

 

[JC1]

You can switch whenever. Are you trying to fix something, just curious or something else by switching to synthetic?

There could be increased oil consumption or leaks. If you are the type of person that checks their oil level regularly then do it. If you just get the oil changed and never check the level I wouldn't do it. Last thing we all want to hear is that you switched to synthetic and your motor is Toast.

Personally I've had cars from a 1984 Toyota Tercel that I switched to synthetic for Winter cold starts and my 1997 Civic uses synthetic during winter and conventional during summer months right up until December. No real consumption issues on that motor.

Your QS oil is probably semi-synthetic anyways. What weight of oil are you using on the two vehicles?

 

[Pinoak]

Why fix what's not broken. Besides QS HM as a real good shot of moly.

 

[gregk24]

Synthetic doesn't cause leaks in a healthy well maintained engine. If your engine is sludge up and is sealing a leak up, then synthetic (or even fresh conventional oil) may clean up the sludge and expose the leak, but it's not the cause.

 

[WagonWheel]

I switched our 2006 Ody to "full synthetic" at over 100k miles, mostly because it is cheaper after rebate. Pennzoil Platinum. No issues with leaks or oil consumption and at almost at 120k now. The Honda J35 V6 is not finicky about oil as long as it's API rated.

 

[Dave9]

Originally Posted by gregk24
Synthetic doesn't cause leaks in a healthy well maintained engine. If your engine is sludge up and is sealing a leak up, then synthetic (or even fresh conventional oil) may clean up the sludge and expose the leak, but it's not the cause.


"Healthy well maintained engine" is an arbitrary misunderstanding. There's nothing related to this under maintenance except the right OCI for the environment. Given that, seals still wear, healthy for a 200K mi engine is a different standard than for a 30K mi. engine.

In fact synthetic oil does cause leaks. You might be a fan of it and try to defend in some disqualifying way but the fact is that putting it in an otherwise functional engine without leaks can cause them. It is funny how people try to leap over this undeniable truth. Even if sludge is stopping a leak, if synthetic clears that away, it is causing the leak. Nobody said "synthetic caused the gap" that is leaking, rather it is causing the leak. It's entirely 100% true that synthetic oil causes leaks.

Now if you want to debate whether a leaky engine running synthetic with less sludge in it is better, that's a different argument.

The question is, why were the vehicles switched to high mileage oil? If it was because of leaks (or burning oil) then it is expected that sooner than later, use of a synthetic non-high-mileage oil WILL increase leaks or oil burning. Use of a synthetic high mileage oil should decrease that. On the bright side if leaks become excessive, switching back to non-synthetic high mileage oil should reduce leaks eventually, and waiting for them to slow is a better strategy than pouring thick goop in the oil to increase viscosity, except that if it's burning more oil you may end up with fouled O2 sensors and a ruined catalytic converter(s).

 

[ka9mnx]

What are you trying to accomplish?

I switched my F150 when I bought it from the original owner in 2003 (182k miles). Switched the 4Runner when I bought it from the 3rd owner in 2017 (245k miles). Nothing bad and all good. But I had a reason, longer drain interval, better fuel economy, longer engine life and it's what I've done since 1974.

 

[Indywar2]

Thank you for all the discussion on this topic.

The F150 has 178,000 miles and the Honda 155,000 miles. The truck seems to burn a minor amount of oil between changes (~6 months), the Honda has been running good. I ask the question to understand if switching to synthetic significantly increase engine longevity/dependability.

I also inquired about the issue with synthetic causing leaks (for those arguing the synthetic don't chemically cause the leaks, that is a difference without a distinction; the end result is a leak that did not exist previously) as there were some concerns online that older engines where leaks developed after switching to a synthetic motor oil.

Thanks again for the responses and discussion.
Rob