Originally Posted By: SuperDave456
Modern day conditioners/high mileage oils should not hurt your seals. From what I understand the HM oils have a more robust add pack and are thicker for their particular grade. You wont find the "energy conserving" doughnut on the bottle due to it being thick for that particular grade.
Supposedly they have more cleaning agents, but I figure that is part of the add pack. Everything has "More CLEANING AGENTS!!!" these days.
The added polarity of some esters (or an additive that has more polarity than a typical engine deposit) acts as a cleaner because it can attach itself to metal parts while loosening up old deposits.
That is what you are paying a little extra money for. A more robust add pack.
Now if you have a truly old car with cork gaskets, or you have a damaged gasket, I can't help you. You will either need a mechanic or an exorcist.
But on a more modern vehicle with modern gaskets from what I have heard it does a good job. I have run a few OCI's with both Maxlife and the QS High Mileage and have not had an issue. My father has run them in his car too, no issues.
The entire "will make your gaskets explode" came from older additives and older gaskets. Bitten once twice shy. Kind of like the Pennzoil is Wax junk you hear once in awhile that wont die. You can make cork swell much more easily than the rubber coated steel gaskets they use today.
BTW, I just did a transmission service, drain pan, new filter and inline cooler with a Magnefine filter, on a 1980 Dodge Van that has been modified into a 20 passenger bus. The transmission had the original transmission gasket. Very brittle cork.
Interesting that it could last so long. The previous owner really neglected it, but that is a different story.
My oil adds are
1. VSOT (on my last bottle)
2. Schaffer's Moly EP
3. (something I don't want to get flamed for)
4. Experimenting with MMO
5. Thinking about that Lubro Moly stuff even though I can get Schaffer's Moly EP stuff CHEAP.
Thank you