Switching from High Mileage to non High Mileage

[Dehaka]

a short list of what it could be:
poor gasket materials, QC on these parts is abysmal.
assembly errors
warped gasket surfaces
incompatible expansion rates due to dissimilar engine materials
Sealant on gaskets where none is called for
out of range of the preferred ambient air temperature during assembly
assembled parts contaminated with dirt, oil, grease, or oily fingerprints.
…..the list could go on and on.

Suffice it to say that I doubt the pronouncement of anyone who makes the generalization that X causes Y without more evidence than what your fishing buddy mechanics have provided. The majority of vehicles, using the same type of oil that you were warned against using, have no issues.

Anecdotal outliers are not proof of anything.

Riiiiight but they're saying this is a frequent thing with other customers and is supposedly general knowledge. I've heard it before but read stuff to the contrary that basically parrots what you're saying.....and to be honest the argument from your perspective seems more logical.....but real world experience for me tells me otherwise. Like I said these engines run great on the stuff.....i wished that your point of view was my expierence.
But I'm switchjng back to blends.....all I'm looking for is other peoples reL world expierence in going back to.non high mileage from high mileage and if it made leaks worse.

 

[RyanY]

Riiiiight but they're saying this is a frequent thing with other customers and is supposedly general knowledge. I've heard it before but read stuff to the contrary that basically parrots what you're saying.....and to be honest the argument from your perspective seems more logical.....but real world experience for me tells me otherwise. Like I said these engines run great on the stuff.....i wished that your point of view was my expierence.
But I'm switchjng back to blends.....all I'm looking for is other peoples reL world expierence in going back to.non high mileage from high mileage and if it made leaks worse.

Well, my experience includes three cars that have been on HM or non HM since their youth, depending on what was in sale. However, I never stuck to one brand/type long enough to know whether long-term HM use would cause problems.

Another question is what, if any, repairs/replacements were done on these engines?

 

[Ant On Tuba]

M1 HM 5 - 20 during winter, engine is quiet warming up (30's), regular M1 5 - 20 or 5 - 30 test of the year. '10 Sonata 2.4 374k

 

[Dehaka]

Well, my experience includes three cars that have been on HM or non HM since their youth, depending on what was in sale. However, I never stuck to one brand/type long enough to know whether long-term HM use would cause problems.

Another question is what, if any, repairs/replacements were done on these engines?

1 head gasket job on the buick engine.....other than that they've all been gasket or seal replacement jobs.....most of them have had oil pans, rear mains, and timing covers done.....on engine work, anything done with the exception of the headgasket job was chasing oil leaks. I've patched a ton of leaks and then new ones spring up.

 

[RyanY]

1 head gasket job on the buick engine.....other than that they've all been gasket or seal replacement jobs.....most of them have had oil pans, rear mains, and timing covers done.....on engine work, anything done with the exception of the headgasket job was chasing oil leaks. I've patched a ton of leaks and then new ones spring up.

That's a lot of leaks! I have three cars around 160k each and never had any oil leaks (knock wood). The only gasket replacements were those necessary for a timing chain job on the Cadillac, and the intake gasket on the Toyota.

It's hard to know why yours had so many leaks, other than the cars' ages and/or gasket technologies; that era of GM cars had gasket issues with Dexcool, but I don't know if the other gaskets had any frequent issues. If you used aftermarket replacements, did any of these spring leaks, or did only the original gaskets leak?

 

[Dehaka]

That's a lot of leaks! I have three cars around 160k each and never had any oil leaks (knock wood). The only gasket replacements were those necessary for a timing chain job on the Cadillac, and the intake gasket on the Toyota.

It's hard to know why yours had so many leaks, other than the cars' ages and/or gasket technologies; that era of GM cars had gasket issues with Dexcool, but I don't know if the other gaskets had any frequent issues. If you used aftermarket replacements, did any of these spring leaks, or did only the original gaskets leak?

its only been a year and a half since the oldest ones were replaced. though buick did have oil pump replaced a few years ago and that leaked again after not leaking. havent had any coolant leaks to speak of.....no tranny leaks either and I've been using mobil dm blend in all of the trannys.
guys are right by saying it's not fair to judge if synthetic oil proliferates leaks by a sample of only 4 vehicles.....but it's 100% of the vehicles i own. i thought it was b.s. too.....but the situstion says otherwise.....and i know a few people who have the same engines I do that don't have this many leaks....mechanics tell me the same thing so.

 

[Fishstyx]

a short list of what it could be:
poor gasket materials, QC on these parts is abysmal.
assembly errors
warped gasket surfaces
incompatible expansion rates due to dissimilar engine materials
Sealant on gaskets where none is called for
out of range of the preferred ambient air temperature during assembly
assembled parts contaminated with dirt, oil, grease, or oily fingerprints.
…..the list could go on and on.

Suffice it to say that I doubt the pronouncement of anyone who makes the generalization that X causes Y without more evidence than what your fishing buddy mechanics have provided. The majority of vehicles, using the same type of oil that you were warned against using, have no issues.

Anecdotal outliers are not proof of anything.

Without empirical evidence everything is just an opinion and nothing more than that.

 

[Dehaka]

Without empirical evidence everything is just an opinion and nothing more than that.

Uh huh....and who's going to prove that point? Empirical evidence is likely unobtainable as the evidence will always be skewed toward the contrary, despite factual observations in everyday, real life applications.
No oil company is going to say : "Our highest price synthetic may clean your engine too well and cause leaks, so buy the cheap stuff instead".....car companies won't say: "Don't use synthetic oil as it's increased protection will lengthen your engine life, thereby elevating our reputation among consumers of making long lasting engines, buuuut it may clean sludge that was preventing a leak." Easy to shake a finger and say show me proof....harder to justify what anyone would have to gain by actually showing that proof.
Everyone calls it a myth and old wives tale....but it likely has some basis in factual real world expierence. There are too many examples and stories of people who say it's happened to them for it to be an old wives tale. These are likely people like myself who WANTED to use synthetic as they wanted the best protection available for their engine.....but found that a side effect of that was a leaky engine. And them someone on the internet declares B.S. .....which is why I didn't bring it up in my original post.....I just wanted to know about switching from HM oil to non HM.



have had several members here private message me saying that they've had the exact same experience with leaks appearing after switching to synthetic.....but that they don't wanna post on this thread as they'll be met with pitchforks and torches basically.

 

[RyanY]

its only been a year and a half since the oldest ones were replaced. though buick did have oil pump replaced a few years ago and that leaked again after not leaking. havent had any coolant leaks to speak of.....no tranny leaks either and I've been using mobil dm blend in all of the trannys.
guys are right by saying it's not fair to judge if synthetic oil proliferates leaks by a sample of only 4 vehicles.....but it's 100% of the vehicles i own. i thought it was b.s. too.....but the situstion says otherwise.....and i know a few people who have the same engines I do that don't have this many leaks....mechanics tell me the same thing so.

I think this discussion includes some very important info for anyone who owns a 90s era car that originally specced dino oil. My cars are 2005+ and received syn/blend since day 1 so this is not necessarily relevant to my current fleet, but it is interesting nevertheless.

From what I have seen from most sources on the interwebs, the general consensus is that older gaskets become worn after years of dino oil which does not lubricate as well as syn oil, and also allows some sludge buildup if not changed frequently enough; switching to syn then removes any sludge that previously kept the seals functional, or otherwise seeps into cracks/gaps that dino oil did not, resulting in a leak. In other words, syn oil reveals a leak that was masked by dino. As mentioned above, we do not have empirical evidence to directly test this claim, but it could be addressed if the following question is answered:

Have any of the four cars in question exhibited repeat leaks from the same location as the previous leak (RMS, valve cover, etc)?

If only old seals leak, then it is likely that the general consensus (above) is correct. However, if the new seals also leak, then several possibilities exist:

1. The component (crankshaft, valve cover, etc) is damaged or has a groove worn into it, preventing a new seal from mating with the surface.
2. The new gasket/seal is of poor quality (fake part from ebay/amazon).
3. The new part was installed incorrectly (wrong sealant, bolts not torqued to spec, wrong tool damaged the seal, etc).
4. Syn or HM oil damages gaskets/seals and causes leaks.

I can't say which of these possibilities is correct, but I have my biases/presuppositions...

 

[Dehaka]

I think this discussion includes some very important info for anyone who owns a 90s era car that originally specced dino oil. My cars are 2005+ and received syn/blend since day 1 so this is not necessarily relevant to my current fleet, but it is interesting nevertheless.

From what I have seen from most sources on the interwebs, the general consensus is that older gaskets become worn after years of dino oil which does not lubricate as well as syn oil, and also allows some sludge buildup if not changed frequently enough; switching to syn then removes any sludge that previously kept the seals functional, or otherwise seeps into cracks/gaps that dino oil did not, resulting in a leak. In other words, syn oil reveals a leak that was masked by dino. As mentioned above, we do not have empirical evidence to directly test this claim, but it could be addressed if the following question is answered:

Have any of the four cars in question exhibited repeat leaks from the same location as the previous leak (RMS, valve cover, etc)?

If only old seals leak, then it is likely that the general consensus (above) is correct. However, if the new seals also leak, then several possibilities exist:

1. The component (crankshaft, valve cover, etc) is damaged or has a groove worn into it, preventing a new seal from mating with the surface.
2. The new gasket/seal is of poor quality (fake part from ebay/amazon).
3. The new part was installed incorrectly (wrong sealant, bolts not torqued to spec, wrong tool damaged the seal, etc).
4. Syn or HM oil damages gaskets/seals and causes leaks.

I can't say which of these possibilities is correct, but I have my biases/presuppositions...

yes 2 leaks have resurfaced and were warrantied and do not currently leak.

that bit you said about conventional not properly caring for seals in the first place and likely turning acidic seems VERY plausable to me. Thank you for that perspective.

no rms leaks after repair.

all gaskets were felpro from rockauto, parts geeek, dealer or auto part store....no exceptions. All seals were OEM from dealer no exceptions. my mechanics allow me to bring my own parts because i only buy the best i can get and don't let price factor into my parts.

on ford, oil pan leak that poped up a second time, we put a new oil pan on just to make sure mating surface was perfect....no leaks since then. on buick timing cover......mechanic showed me the seal and it looked fine but new seal didnt leak.

I think you hit the nail on the head for my problem. even though they were old cars.....i always bought either Ford raceing or ac delco professional/gold filters and wally world motocraft and local dealer sourced ac delco oil (for gms) prior to researching oil and trying synthetics after begining to research oils and finding this place.

96 f250 5.8 I've had since 17 k miles. no idea on service history prior to my acquisition.....but only had 17 k. now has 65k

03 buick century got with 70 k was bought new off the lot by my granny in 04 as it was left over stock and was serviced at dealership every 6 months or when olm light kicked on until i got it about 2.5 years ago. now has 99 k.

03 deville got with 73 k owned by an older lady who basically did the same as above car and i obtained a print out of its whole service history when i took it to the local dealer it originally came from (few blocks from my house) to replace the ignition cylinder. same as above buick.... oci when olm kicked on. this car had an occasional drip from the oil pressure sensor but stopped when was replaced upon purchase. Now has 111 k and is a leaker.

98 jimmy bought with 107 k from mother whos husband passed away.....he bought from an old lady who kept detailed service records on it. did get some dealer service but mostly serviced at a garage that gave it quaker state most of its life.....have a thick paper file from moms husnand and original owner. now has 113k.

it was very strange....i basically bought 4 cars in 5 years and ran them with conventional and oem high grade filters for a few years.....with 0 leaks...85% highway driving. Then in 2021 I leaned about synthetics and High Mileage oils and made the switch thinking I was doing a good thing.....trying a different brands (m1 hm ep x2, castrol edge hm, and pennzoil platinum hm) and going with puro boss, mobil 1, wix xp, and k&n filters in 6 month intervals never hitting 5500 miles on any of them. and since about 4 months into switching up to now....the leaks haven't stopped.

 

[Fishstyx]

Uh huh....and who's going to prove that point? Empirical evidence is likely unobtainable as the evidence will always be skewed toward the contrary, despite factual observations in everyday, real life applications.
No oil company is going to say : "Our highest price synthetic may clean your engine too well and cause leaks, so buy the cheap stuff instead".....car companies won't say: "Don't use synthetic oil as it's increased protection will lengthen your engine life, thereby elevating our reputation among consumers of making long lasting engines, buuuut it may clean sludge that was preventing a leak." Easy to shake a finger and say show me proof....harder to justify what anyone would have to gain by actually showing that proof.
Everyone calls it a myth and old wives tale....but it likely has some basis in factual real world expierence. There are too many examples and stories of people who say it's happened to them for it to be an old wives tale. These are likely people like myself who WANTED to use synthetic as they wanted the best protection available for their engine.....but found that a side effect of that was a leaky engine. And them someone on the internet declares B.S. .....which is why I didn't bring it up in my original post.....I just wanted to know about switching from HM oil to non HM.



have had several members here private message me saying that they've had the exact same experience with leaks appearing after switching to synthetic.....but that they don't wanna post on this thread as they'll be met with pitchforks and torches basically.

Go look up Lake Speed Jr. on YouTube he’s far more authoritative than the vast majority of people here. He actually uses empirical evidence to support and show how oil actually works.