It's a product of BG. BG109 in their stocking list. Now known as EPR (Engine Performance Restore). It works well in most cases. But this is an unusual one ...
Listen to your mechanic. Get your evidence from Blackstone. Get ready for XOM to deny anything having to do with this. You did not buy it from them (ie XOM jobber), you bought it from a retailer. It passed through many hands. Anyone could have fooled with the mix ...
Someone might have injected something through the edge of a foil seal and you would not have seen it. Prolly took engine heat to set it off ... The more you drove, the thicker it got. Now you have gel.
But, if it was mixed with motor oil (?), you had some lubrication until you got a check engine light. So the engine may live. Yes, it was compromised. Yes, it will prolly not live as long as it could have. But, it may run fine for many, many miles ...
The issue is, can it be flushed? I'm not a fan of flushing engines. I think a decent oil will keep it clean enough normally. But this is an extreme case ...
So what to do? First, get a sample of the goo. Maybe more than one. Find something that will soften it, or liquefy it?
I'd start with Kerosene. It's pretty benign. It is the native solvent for all sorts of adhesives. It has some lubricity (not a lot). If Kerosene will liquefy the material, then you/your mechanic can fill the engine to the valve covers with a mix of Kerosene and Marvel Mystery Oil (MMO), which is a pretty decent low grade solvent by itself (with better lubricity). Start the engine and run it a few minutes at idle,
Now put on a new filter and a decent semi-synthetic oil like Maxlife 10w30 and full can of BG-109. Drive it cautiously around the block. Listen and look for odd sounds, fluctuating oil pressure (have a gauge installed temporarily). Pull the filter and see what it looks like? See what the oil feels like? Any color changes? In this case I might go with something like Royal Purple so I could actually see color changes quickly ...
If all seems normal, you may have dodged a bullet
If something seems off, you may now try to figure out what that is (variable cam phasing, etc.) My guess (no bets) is that it will run as normal, maybe throw a code or two ...
You will have to baby it for 100 miles, then change the oil and filter again and use BG-109 each time until you are confident that the goo is gone. Once you are confident, just drive it
-> Just a note, and I don't know if this is still the case, but the Valvoline Maxlife jugs I just used (in storage more than a year) had very well attached foil seals. Like really well stuck. If you can find current jugs of any appropriate oil with really good seals, use them from now on
And, just in case no one thought of it, this could all be from a filter in the store with powdered glue inserted as joke ... The Mobil 1 may have been fine. You could have screwed on a bad/"joke" filter and it would have come out the same. There is no way to be sure of the source here ...
Maybe someone does not like Toyota/Lexus (1%'ers, you know ...) and they targeted the filters that fit that engine ...
