Do engines get "addicted" to HM oils, true or myth

Pennzoil motor oil
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FCD

FCD

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I have seen this argument circulating around the internet, apparently they claim that once you start using High Mileage oils because of the extra seal conditoning additives, the engines get "addicted" to these additives, and if you switch to a non High Mileage oil it will start to leak oil, just seems like another unfounded myth to me, what does BITOG think about this?
 
Wow ..... Seems like you created this thread on my behalf. Thx
The question asked is the exact reason I am hesitating using High Mileage oil on my 2003 Honda Accord 4 Cyl . Although the kms are only 137000 on it but it burns oil . Even though there is no Leak ( I believe that preventing leak is where the High Mileage oil works its magic), I am getting inclined to use Valvoline MaxLife Synthetic Blend... Reason - It has good reviews and it is cheaper than Mobil 1 that I am using right now and I do not need to look for deals ...But will I be married to this High Mileage oil forever ?

And if I am not derailing the thread much ... Is the only reason one should switch to High Mileage oil is to prevent leaks? If the engine is not leaking , should I just continue running normal oil?

TIA
 
A car that leaks oil might start to leak again once you take it off a High Mileage oil.
 
Myth ... The seal conditioners might soften an old seal some, but as soon as they are gone, it will take time to revert and harden again. They're not that aggressive ...
 
A few years ago it was truth. At least for Mobil 1 high mileage oil it was. Seal conditioner was used in the description, but on the Mobil 1 website FAQ the words seal sweller and swelling the seals was used multiple times to answer multiple questions. Unfortunately I can't prove it because the Mobil 1 website has been merged with Mobil oil and the FAQ has been deleted. I have no reason to lie about it. I'm sure there are others that remember the discussions.

My personal experience with Mobil 1 High Mileage is truth. It mostly stopped valve seal smoking and consumption. And it also stopped a leak at the oil pan Which is factory form a gasket. I can't imagine how a seal conditioner would effect form a gasket material. Would think it's because of a swelling agent.

So IMO if you don't need it don't use it. Modern oils are just fine on their own for the seals
 
I'm trying Pennzoil High Mileage on my Subaru with a rear main or oil separator leak. Doesn't drip on the ground, just onto the exhaust and smells awesome, and the repair is serious cash for a minor mechanical issue.

But I do expect to go back to non High Mileage oil if it doesn't do anything.
 
IMO, it will revert. But it might take a long time to get back to where it was before the High Mileage oil change. I see no downside to just sticking with MaxLife Blend on an older car. It's a high quality product and will be available for a long time to come - it's the best selling High Mileage oil.
 
Originally Posted By: Hollow
I'm trying Pennzoil High Mileage on my Subaru with a rear main or oil separator leak. Doesn't drip on the ground, just onto the exhaust and smells awesome, and the repair is serious cash for a minor mechanical issue.

But I do expect to go back to non High Mileage oil if it doesn't do anything.


I've never used Pennzoil High Mileage but I can tell you using other High Mileage oils it takes awhile to see results. Usually towards the end of the second oil change/10k so be patient
 
I think it's a big old myth... Many (if not all) garages & quick lubes that carry Valvoline products use MaxLife Blend as their synthetic blend whether the car is a 2016 with 5,000 miles or a 1995 with 300,000 miles. MaxLife meets DEXOS requirements for new GM vehicles as well as Chrysler & Ford specs. I don't think they'd tell you to use this high mileage oil in new engines if it was going to harm anything in the long run. I have seen people switch back & forth between regular & High Mileage oils with no ill effects. I have 8 quarts of MaxLife ready to go in my 5.0 F-150 at 20K miles.
smile.gif
 
Well, think about it logically, if your seals expand based on the oil and it stops some leak or consumption. When you switch to a different oil that benefit will go away and the issue will return so I think the word "dependent" is appropriate.
 
I have used all kinds of oils on my 2005 Buick, L3800 engine,,,it loves them all, still runs great, what can I say..
 
Again, like others have stated, nooooooope. Not at all.

I bought my 2002 Jeep 4.0 with 85k miles on it. I have been using Pennzoil High Mileage since then racking up now to 134k miles. It's mostly seen Pennzoil High Mileage but I do fancy Pennzoil conventional every once in a while and nothing has ever changed. No drops/drips or any kind of oil consumption using the Pennzoil conventional.
 
I did a run or two with high mileage in mine because the oil pan gasket was leaking and I didn't want to change it. Turns out someone else changed the rear main seal and forgot to tighten all of the pan bolts and that was causing the leak - High Mileage oil can't fix that.

Went from QS Defy right to Supertech synthetic and no extra leaks / burning.
 
Originally Posted By: FordCapriDriver
My oil pan used to weep slighly at some places, when i went to a HM it stopped, but then again i also went from a 10w40 to a 20w50 so that was likely it


If the oil pan was weeping then I'd attribute the success to the HM over the thicker grade in my opinion. Most likely a combo of both. You should have tried one or the other first lol.

If it was weeping a little bit then I would bet it would start weeping again if you switched off high mileage. This might not be the case with the thicker oil but I would think so if you switched back to the 10w40
 
I think the argument is unfounded. If high mileage oils rely on seal swelling agents, as others have suggested, then the worst that could happen is that the seals would shrink back to their original size over an extended period of time. That might be quite a while. Eventually the seals would return to their original dimensions; it is hard to imagine them moving to some state that is worse than where they started before High Mileage oil.

For what it is worth, our 2001 Volvo V70XC has been using Mobil 1 5w30 High Mileage for the last four years. Several weeks ago that was changed to Mobil 1 0w40 for towing season. The plan is to keep it that way throughout towing season, then go back to 5w30 High Mileage for the winter. I am happy to report that after 1000 miles of driving, including 500 miles of highway speed towing, the engine hasn't blown and there are no signs of new oil leaks. I will check back in a few months and let you know if that changes.
 
@Astro-Guy Good to hear! But why not use Mobil 1 10w40 HM for towing season? But I guess if leaks don't reappear then you're doing things right.
 
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