I did, and most of what I was finding was either incomplete, or would support the whole over full situation I was talking about. simply saying that "I added lucas to my oil" doesn't mean that they drained out a quart before hand. Simply over filling your engine with oil will cause all of the same problems. I wasn't finding anything that said anything that would have been specific to the lucas stuff itself.

I think we are saying the same thing here. Yes, synthetics are more resistant to the temperature changes. But a 10w30 is a 10w30 synthetic or not. it is 10w30 when it is cold and 10w30 when it is hot. Now, really really hot and really really cold of course alter that, however, just because it is synthetic, doesn't mean it is going to be better. There are some mineral oils that out perform many synthetics when it comes to extreme temperature performances.
I wish I still had those data sheets... maybe I'll be able to find them later.
Point being, by the time you get cold enough to thicken the oil up that much, I doubt you would be worried about driving a performance car.
I was simply trying to point out that the thought that synthetic oil is "thinner" is not true. If it is rated to be a 10 weight, it is the exact same as its mineral counterpart. The difference being, the synthetic can be more resistant to the extreme temperature differences. It won't thicken up as bad as a mineral oil will in the extreme cold, and it won't burn off, thin out, shear apart, at the same temperature as a mineral oil. Synthetics typically have a flash point much higher than mineral oil.

a multi weight oil breaks down. period. synthetic or not. the polymers eventually break down and instead of a 10w30, you're left with just a straight 10 weight. but at that point, enough of the oil has burnt up, and sheared apart that it has the viscosity far below 5 weight, and lubricates even less.
synthetic is simply more resilient than mineral oil. (again, this is a case of most synthetic and most mineral as some mineral outperforms synthetic) Because it is more resistant to the temperature changes, the polymers don't "relax" and "contract" as "easily" as the mineral oils do, so they don't wear out as fast. The polymers act just like a spring, and just like all springs, they eventually wear out. I know, it is a very very simplistic way of thinking about it, but that's pretty much how it works, in a nutshell.
So with that said, I will agree with you, the actual molecule itself doesn't break down. (it can get sheared apart, but that isn't the same as just breaking down) However, the polymers themselves are what break down. Once those breakdown, the oil won't thicken back up when it cools off, it will be in its thinnest form all of the time. continued use of broken down oil, eventually leads to the oil sludging up. It breaks down, shears apart, burns up, etc.
If synthetic oil never broke down, then why do you have to change your oil at all? I mean, If the oil itself doesn't break down, then why not just change the filter every few thousand miles and call it even? The additives, and detergents and all of that will eventually all break down, but they will be caught up in the filter. And the chunks of carbon from blow by can be filtered out. If the oil says at 10w30, then it would suspend any deposits long enough to get through the filter. A good filter would be able to pull all of that stuff out. If the oil isn't ever breaking down, then you could go 8, 9, 10 or more thousand miles on a single oil change, just gotta change the oil filter every so often. You would only need to change the oil when enough of it gets burned, and since synthetics have such a high burning point, that could take a while.
Not trying to be a dick, just making a point.
I know it sounds rudimentary but try it. Test it for yourself. Get a fresh bottle of whatever synthetic you are using. After about 2-3 thousand miles, take a little bit of the oil from the dipstick and rub it between your fingers. Do it first thing in the morning after the car has been sitting all night so it is nice and cool. That's when the oil should be at its thickest. Then rub a little bit of the new oil between your fingers. Compare the way the two samples feel. The old oil should feel a bit thinner. As if you don't have to press as hard to get your fingers together. It doesn't feel like it fills in the ridges of your fingerprint as well as the new oil. The new oil should even feel more slippery. If it doesn't, then make a note of it, and put some more miles on it. Depending on the oil and the condition of the engine, it could take several thousand miles. Like I said on the first page, that 4 door GSR integra I was working with for a while, we ran Mobil1 in it and it would last 7-8 thousand miles before it started to break down. The point is, you'll eventually feel the difference between the new oil and the old oil.

The point I was trying to make is that a weighed down semi truck has a lot more stress on the engine and turbo. So if the lucas was causing a problem because of a reaction to the heat then it would be more evident from a turbo that is red hot for hours at a time, more so than a boosted car that probably only beats on the engine enough to get the turbo that hot a handful of times its whole life. I also assumed that there would be more recorded issues with it related to semi trucks as it is much more commonly used in semi trucks than it is in cars.
The only issues I was finding related back to cars all seemed to anecdotal or they stated things like "I added lucas to my oil and my turbo blew up" Which is why I want on to theorize that those people probably just added a quart of Lucas to their already full oil pans which is what really caused their problems. I even found one where the person used only lucas and no oil. I think 4 or 5 quarts of that stuff would cause problems given just how thick it is. It makes 80w90 look like water.
Most all of the problems I was finding were all of the same, generic, "I did this to my car, and the engine blew up" type of stories. You can find as many horror stories of people's engines and turbos blowing up from using any brand of oil. I love the "Synthetic oil sucks, I used that crap and I tossed a rod" stories. Point being, if you look, sometimes not even that hard, you can find horror stories about anything.


Thats what I get for posting from my phone and not paying close enough attention. I meant mechanic in a can.



From what I can tell, Lucas stuff aside, you seem to be on the right path with what you're thinking about oil and all of that. you're just missing a few pieces. Like with the whole synthetic molecules don't break down. Well, that's pretty much true. Aside from burning off and shearing apart, they don't just "wear out" The part that does is the polymers that hold it all together.
So even if you only have 80% of the whole pie, that is still 95% more than the most people. so kudos for that.