Who has actually switched to synthetic oil, and experienced seal leaks?

[sakoluvr]

I have read on the Mobil 1 site and elsewhere that the earliest versions of Mobil 1 could indeed cause some issues with seals when switching over to synthetic on higher mileage motors. The later formulation of M1 not being being an issue.

I recently switched to "high mileage" M1 in a 2001 T4R (160,00 miles) and a 2000 F150 (130,000 miles) after using regular oil for years. No problems noted.

I have a '97 T4R that I recently purchase (260,000 miles) and I am going to switch to the same Mobil 1 high mileage.

The container says that it contains additives for the seals.

Who has changed over and knows for a fact that Mobil 1 caused leaks? Did you use the high mileage M1?

 

[Whitson Metalworks]

i run full synthetic M1 in mine (250K) and the only thing that leaks are the valve covers, which is common anyways. I also use it in my wife's (190K), no issues there.

 

[LittleCaesar]

These engines will run on about anything out there. That said, given the age of 5vzs, leaks can be more prone to occur in engines whose gaskets are 15 years+.

Concerning the high mileage M1, I'd say use it with confidence. Their 10w-30HM has a great add pack. I am using the aformentioned oil in a Bronco with a leaking (rather noticeable) oil pan gasket and the additives in the oil have aided I think in some degree in slowing down the leak to a trickle, thus giving my lazy self more time to do other things.

 

[Brian757]

I have been running synthetic for about 1,000 miles. I converted about a month ago. Not a single issue. I am using Castrol synthetic oil.

 

[sportscarfan]

No leaks on my 4runner - I got it at 174K and it's now got 194K. I've run standard Mobil1 since purchase.

 

[Ruiner]

i switched to M1 (150k miles) and no more leaks than i had before. It was leaking a bit from the rear main seal before, but it hasnt leaked anymore or any less since the switch

 

[Shibby!]

Chances are if it leaks there was an issue anyways.

250,000 KM, been running synthetic for the last 20,000 KM's (Castrol Edge, Rotella T-6, and Mobil - whatever is on sale)

No issues. Valve covers seeping very lightly, not a concern of mine. I keep it clean and an eye on it but valve covers tend to leak on almost everything.

 

[JohnsD90]

I don't see a need for change, I just used regular Shell or Mobil 5w-30. I have no interest in dealing with leaks on a 14 year old truck.

 

[Whitson Metalworks]

I don't see a need for change, I just used regular Shell or Mobil 5w-30. I have no interest in dealing with leaks on a 14 year old truck.

i dont think it would cause any more leaks than were already present. Plus, dyno oil breeds sludge and crazy amounts of carbon build-up, google some pics of sludged/carbon'd up valvetrains, its something i hope to avoid for sure.

 

[JohnsD90]

i dont think it would cause any more leaks than were already present. Plus, dyno oil breeds sludge and crazy amounts of carbon build-up, google some pics of sludged/carbon'd up valvetrains, its something i hope to avoid for sure.

Non-Syn of yesteryear is different than that of today, i've pulled valve covers and oil pans off motors running Non-Syn and they look very clean even with high milage. Many professional mechanics have told me to keep running the Shell/Mobil Non-Syn motor oil, and i won't have issues, and to not switch this late in the game.

 

[Steve240]

from what I understand the syn oils have smaller molecules which are why people say they will leak on older vechiles. I switched to syn oil as soon as I purchased my 4runner. oil lastest long and should improve mpg although I never got a baseline on convential too see if that held true. imo if it leaks with synthenic it will be a small leak you will have time to fix before it's a big issue. If you keep running conv oil until it leaks you may have a bigger problem that requires immediate attention = money. My valve cover has leaked since I purchased the 4 runner but it's very minor, I plan to redo the gaskets this summer once I find the time.

 

[JohnsD90]

from what I understand the syn oils have smaller molecules which are why people say they will leak on older vechiles. I switched to syn oil as soon as I purchased my 4runner. oil lastest long and should improve mpg although I never got a baseline on convential too see if that held true. imo if it leaks with synthenic it will be a small leak you will have time to fix before it's a big issue. If you keep running conv oil until it leaks you may have a bigger problem that requires immediate attention = money. My valve cover has leaked since I purchased the 4 runner but it's very minor, I plan to redo the gaskets this summer once I find the time.

The synthetic brakes down the minor build ups at the seals that have over time created seals for the motor, once they are broken down the oil can then leak, or something like that. Some motors I will only run synthetic in, but a 14 year old vehicle with 200k that I just bought is not one of them. I did put synthetic gear oil in the transmission, transfer case, and diffs though.

 

[Nashvegas34]

I switched to full synthetic at around 90k miles. I have 206k now. No problems at all except for the pesky valve cover gaskets seeping just a bit. I've mainly used Pennzoil Platinum 5w-30, but occasionally used Mobil1 if it was on sale.

 

[sakoluvr]

OK guys, thanks. From all those that have actually answered my question (you know who you are) with no speculation but actual experience, there does not seem to be anybody "Who has actually switched to synthetic oil, and experienced seal leaks".
:amen:

 

[KidVermicious]

I started running Mobil1 in a 22re with 220k and got leaks. I went to Castrol high mileage for a bit and they stopped. This was a while ago.

 

[S Brake]

I run the castrol high mileage blend. No problems so far.

 

[Kanger328]

5W30 M1 Full Synthetic here. I have about 134,000 miles on the runner and switch to the M1 about 500 miles ago. No leaks...so far.

 

[Full_Throttle]

I switch to full syn. when I bought mine 40K miles ago. The only issues I had was a valve cover gasket immediately started leaking. Never leaked before, but within a week I had that burning oil smell. Turns out my cover was loose. I tightened down the bolts to the valve cover, problem solved and leak free for 40K miles.

 

[RonMAIDEN]

I know mine wasn't considered high mileage when I switched over at 100k miles but almost 80k and 9 years later not one drop of any fluid hits the driveway.

 

[Nunyabiz]

Here is the deal about so called leaks from running synthetic oil.
IF you get a leak then you HAD that leak already, or I should say the seal was degraded enough usually because of the regular petroleum oil sludging up areas and effectively drying out the seal which causes it to shrink.

What happens with the synthetic is it cleans this sludge thus exposing the dried seal to fresh oil, if the seal is not too far gone the synthetic can sometimes swell the seal back up, if not then you may get a leak.

I have switched over to 100% synthetic oil on every single vehicle I have owned since 1977 except ONE a 1995 Ford F250 3/4 ton Diesel I used to have.
Unless you add a really nice Bypass oil filter (usually around $300 or more) on diesels then not really worth running synthetic as the diesel dirties up the oil so fast, best to just use Shell Rotella and change every 3000.

Anyway I have had I think 9 other vehicle and all of them switched to synthetic and NONE of them ever leaked.
My 4Runner had 158K on it before I switched to 5W30 Amsoil, no leaks, including gear lube.
I looked in through the oil fill on my 4Runner when I got it and there was a bit of sludge and the previous owner changed the oil every time at 3000 miles as he had all the receipts. In May I will have owned it 2 years, when I look into the oil fill now I see FAR less sludge it is almost cleaned. I am about to do my 3rd oil change in the next couple weeks. First one was the day after I bought it.

There are a few engines OURS being one of them that I would never in a million years run petroleum oil in.
My wife's 99' Lexus is another one that is even worse.
In hers the top end gets so hot that when you turn the engine off and the oil flows down it leaves a thin layer of oil to just literally COOK.
In the Lexus I don't care if you change your petroleum oil every 2000 miles it WILL sludge because it cooks.
The 100% synthetic does not because the flash point is so much higher.