Fight Bore Scoring with 2-stroke oil? (thinking out loud)

Bore scoring scares me more than my original dual row IMSB failing. Knowing that BS is caused by some combination of: frequent cold starts, long oil change intervals, larger bore sizes, failed coatings, leaking FI and maybe some other factors, has adding a high ratio of two stroke oil been talked about? Far fetched? From my ownership of '87 and '92 RX7's, we ran ~100:1 to help the apex seals against the chamber and the later RX8 included oil ports that allowed engine oil into the chamber. Air cooled engines typically run ~50:1 but marine water cooled two stroke engines run 100:1. Amazing technology, really. Similar help for our M96's? Since scoring begins at the bottom of the cylinder, this tells me it is likely the up stroke where it starts, so having lubrication on the top of the rings could be a benefit. Would adding an ounce per gallon (~120:1) alleviate the problem? Or, even a higher ratio? I know, Cat's don't like oil (especially here in CA), but this is equivalent to a quart burned every 700 miles or less, which they can handle (barely) and two stroke oil is not motor oil, it is low-ash intended to burn relatively clean (maybe this is worse for Cat's though)? Plugs? maybe a hotter plug would keep them from fouling? Anyway, I did a quick search here and found nothing but I did find this from a UK forum with the OP asking exactly exactly what I am. Interesting, at least. http://www.911uk.com/viewtopic.php?t...95aaa288e348fb

If you're so concerned with BS, why not get them scoped and take it from there? JR has a diesel oil he recommends using for motors that already have some scoring.

I think most of us are concerned with BS to different degrees, more so my post was about discussing an idea, not "to get them scoped".

Don't know much about this but sounds like an interesting idea. There is really no way of knowing if this will work unless you try it via a long term test. So many variables though. You have people with relatively low mileage cars that have bore scoring and those with miles in the 80k+ that don't. And that's granted that they actually know and have actually done a bore scope. Anything else is just guessing and speculation.

No. Just don�t.

I would be more worried about O2 sensors, rather than the catalytic converters, although I don’t think they would like it either.

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Yeah, not likely to be a viable solution. I doubt it would help if the scoring already started and would require a lot of testing to ever confirm it would actually prevent it starting in the first place. If there is any parallel to the rotary apex seals against the chamber, many RX7 owners swore by it. I bought both my RX's used with low miles and they started "blue smoking" a little over 50k miles. Mazda thought there was something to it though, they included oil ports in the RX8 chambers for engine oil to get in. Regardless, the RX8 failed too. Not comparing the M96 to the rotary here, just thinking of the metal to metal surfaces, coatings, etc and if they are similar. Maybe, but O2 sensors are cheap and cleanable, cats, not so much. 2 cycle oil is designed to be burned while engine oil is not. My son's 03 Pathfinder with 165k miles burns a quart every 800 miles (doesn't smoke) somehow passes CA smog. Maybe 2 cycle engines run hotter so burn without residue only in engines designed to burn that oil, more variables. Gas is not a lubricant either and it strips oil from surfaces so adding even a small amount of oil could make a difference if injectors are even slightly faulty or run too rich (like startup). Incredible technology btw, that Yamaha 2 stroke outboards operate >1500 hrs without a tear down and this allows them to be legal in California. 100:1 ratio turns gas into enough of a lubricant to last so long.

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What you'll do is kill the O2 sensors, and catalytic converters.. You'll also wig the injectors out as they try to meter a more dense fuel.

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Uhh Ohh, I gotta go drain my tank, life time supply of weed eater fuel tho (joke). There's that and carbon build up, but my thinking was who cares if the scoring has started. I don't have any symptoms btw but in my search I saw a couple clearly bad ones with the owner/dealer trying to explain away. One very nice low mile '04 sounded like a diesel, lived in Canada most of its life too. I've got the low temp stat ordered with an early oil change and will drive it like the paranoid person I am.

Copper, vanadium, and sodium are the byproducts of combustion combined with the hygroscopic properties of ethyl alcohol along with the advent of EPA phase III, with the reduction of sulfur in our fuels to less than 30 ppm�.and from what I understand, sulfur is a high-pressure lubricant �� Then add some more misery all SJ, SL, and SM and later oils have been stripped of their effective additive packages to comply with the new CJ 07 oil specs as the EPA claims that zinc hurts emission control components namely the catalytic converter even though these converters have been around since the mid-seventies. Gee, �.is it any wonder why solid lifters, flat tappets, and bore score as well as ring failure is happening?

Anyone ever look at TK7? Used in fleet vehicles and has been proven to work at preventing wear in valve seats, bore, and rings. David Vizzard, a well known engine builder, tested it and said it actually works unlike most additives. Another product of interest is ACES IV gasoline formula. Would be interested in hearing some opinions. Don’t know if this stuff would cause issues with sensors or something, so hoping someone else might have tried it.

I would bet bore scoring is a result of the piston growing too quickly before the cylinder expands.....has nothing to do with lubrication. Don't heat the pistons too quickly by applying too much throttle when cold. wait till it warms up. rpm is ok.....not torque. you can "cold seize" a dirtbike pretty easily. this issue would be exacerbated in cold ambient temperatures

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I haven't heard of TK7 but, other than some Gumout in my past carb'd motorcycle that sat around for weeks, I haven't used any additives much. I did just try some Techron because it was recommended on this forum. Interestingly, unlike Gumout or injector cleaner, it has the viscosity of a thin oil so I wonder if there is an element of 2 stroke protection. I'm not sure if I'll keep using it tho. Yeah, but not all engines experience the phenomenon, or at least not so soon. It would seem it's the nature of the coating (lokasil?), possible defective piston skirt coatings, and then (as you mention) the hotter cylinders are affected first. Also factors are climate, dirty oil and a rich mixture at start up that maybe the additional lubrication might help.

I suggest looking into Driven DT40. The additional zinc & moly makes the oil’s wear package superior to other oils. DT40, and proper driving can help prevent bore scoring. While you’re at it, save up for a proper rebuild.

The only time to use oil additives, is never. That comes straight from API. If you have to use an additive to optimize any lubricant, you are using the wrong lubricant.

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Another big clue is it happens more often the bigger the bore gets.....probably because bigger pistons expand more

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That's right and I believe the Boxster base 2.5 & 2.7 have near zero reports of scoring but the "S" has some instances of scoring at 3.2L. I also recall from the videos the larger bores have a greater oval effect on the thrust side of the bore, where the scoring always begins. Hmm, maybe consider a 2.5L swap and get the underpowered 912 effect as a bonus.

Lots of typical points raised (many very reasonable questions) but most can be answered by reading our technical report on the 4 main causes of engine problems available FOC from [email removed] Baz

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Read the paper Baz and his team wrote. Watch the YouTube video series Jake and his team shot. You will then have post-grad knowledge gleaned from decades of engineering, building, racing and improving the M96/97 engines of all displacements. No stone is left unturned. You will be amazed by the blunders Porsche allowed and by the potential that can be unlocked in the NA flat six.

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+1 on the Baz paper.