Any pics of the VW? Sounds like a fun machine.
I would say that certain engines are not as picky as others. The best way to really tell is through a UOA. However, I still believe that conventional is useless. You can pick up a bottle of Pennzoil synthetic for as cheap as any conventional and you have the longer drain intervals and cold start benefits. I usually change my oil once a year at this point since I never get past 5k in a year.
I've always found Amsoil's marketing quite sketchy. I recall them guaranteeing 25,000 mile oil change intervals. That sounds downright scary.
I think I may have one of the VW (Baja Bug) that I took right after I got it, I drove to the top of Saddleback mountain up the firebreak roads.
That was about 1977-78. I might try to take a digital photo of it.
It was a great "UAV" Urban Assault Vehicle, ran 36" Dick Cepeks in the rear and 35" 8ply sidewall military Jeep tires in the front, If I got a flat (they were tube tires) in the front tires they were so heavy duty and the VW so light in the front that I could still ride at 60 mph on the highway with a flat.
Front end was made from a cadmium dipped VW Thing which is about 4" wider, much taller shock towers and at least twice as beefy as stock VW bug.
Had Porsche deep bucket Recaro seats, full 5 point racing harnesses.
A Berg Warner 5 speed close ratio gearing.
A custom made 25 gallon fuel safe that was the whole back seat area with sight tube in between the seats showing exactly how much gas is available.
A full roll cage from bumper to bumper and side brush guards made by who at the time was THE go to guy for Baja 1000 work (Bill Savage) who made the roll cage, the front end and also custom made shocks specifically for my VW.
They were about 4 feet long in the rear and went up through the pan and connected inside to the roll cage, same with the front shocks, custom made.
Engine was built by Ray Stephens which again at that time in the 70s and 80s was THE guy in the area to build racing VW and Porsche engines in Southern California.
Combined with that Berg 5 it was quick as hell, not fast, top end was wound out at about 85 miles per hour BUT it would do 0-60 in like 4 1/2 seconds.
I could pull the front end off the ground about 6" when I got on it at a dead start. Those giant and sticky Dick Cepeks would just go "Chirp" front end came up and I was gone.
I put in Datsun B210 axles in the rear which were massive compared to the tiny little axles and CVs of a stock bug, it also got rid the CVs as the B210 axles were U joints and had a lot more travel, about 3-4" wider and able to handle a lot more lift.
I remember one time a Supercharged 56 Chevy, the type that gets beside you and your car is rumbling and rattling from the sound of their engine.
I beat him across the intersection which he wasn't really going for it but it still kinda pissed him off so he got right behind me and then gunned it and blazed by me on the left, so I returned the favor and before he even pulled in front of me I had already slammed the petal to the metal and whipped on by him on the left and pulled in front of him.
This was night time, we were doing about 80 in a 45 and I knew this street well, there was a BIG dip coming up was a cross street where the street going across was raised higher in the center and had two full gutters on both sides, so was a gutter DIP then rounded raised area then another gutter DIP.
I hit it as fast as my VW could go about 80-85mph and barely even felt that I went over anything, could have had a full glass of wine in my hand and not spilled a drop.
I look in the rear view and I see his two headlights dip down hard because he was slamming on his brakes, then I saw SPARKS and no headlights at all, what I was looking at was the total BOTTOM of his Chevy with the headlights virtually straight up in the air and then BAM I see headlights and sparks again.
I would imagine that he damn near totalled the frame of that Chevy which was lowered and had that massive engine up front, I am sure his tires were both sticking out like wings.
I had to LMAO.
I agree about Amsoils marketing, do not like it at all, BUT I can not fault the oil.
It is still guaranteed for 25,000 miles in normal driving or 12 months as long as you use a oil filter that can handle that much filtration.
Like you I only drive about 5000 a year and just do a 1 year oil change.
I think the only way that I would let oil go UP TO 15,000 is if I was using a Bypass Oil Filter and was driving nothing but highway miles, even then I doubt I would let it go a full 15,000.