I used SAE 40 a few times in engines that were run for years on conventional 5W30s with the same result.
Some people experience the same, switching to a PAO synthetic following a conventional.
Back in the day we could get Esso XD-3 0W40 with SA 1.5, TBN 12+ and a ZDDP content that would glow in the dark.
I wouldn't be surprised if it had 20% JTO blended in. Aircraft turbine oil used to be the bitog trick of the week.
There is an entire thread that got sideways on the topic, between a USAF officer and a know-it-all mechanic who took home used JTO
and put in his pickup truck.
Some people experience the same, switching to a PAO synthetic following a conventional.
Back in the day we could get Esso XD-3 0W40 with SA 1.5, TBN 12+ and a ZDDP content that would glow in the dark.
I wouldn't be surprised if it had 20% JTO blended in. Aircraft turbine oil used to be the bitog trick of the week.
There is an entire thread that got sideways on the topic, between a USAF officer and a know-it-all mechanic who took home used JTO
and put in his pickup truck.