... and for sure causes a new filled synthetic oil a lot of leaking after a while. This modern stuff used with twenty year old seals gets out of your engine as soon as possible.
We could give you one hundred names of users where it happend exactly like this. May be there are fifteen, who were as lucky as you.
As i wrote, if you examine your engine down to this and replace all seals, then your choice of oil is free.
Yes, agreed. I read on the old forum that changing to synthetic after many years of running regular oil can, and usually does cause oil seal failure.
TheMason must have been running synthetic on both bikes with low milage/age...that's why no leaky seals. OoB
No. One bike I have owned since 1984 was switched from a steady diet of Kendall GT-1 20W50 to Mobil-1 15W50 full synthetic at about the seventeen year point with over 150,000 miles on that engine. No leaks. Another old K-100 was switched to synthetic from dino oil at around 15,000 miles with no leaks ( this bike is the perfect original early K bike with only 22K miles total, my little museum piece ).
Same thing with a 1988 Audi. I bought it in 1993 with 53K on the odometer. The previous owner had been using some crap no-name 30 weight oil. I found a container of it in the trunk. Horrified, I immediately switched it to Mobil-1 and nothing leaked. Never has, and the car has 145,000 miles on it today. Completely oil tight. More recently I bought a 1993 Audi off a cousin with 160,000 miles on it. He used Castrol GT-1. I switched this car to Mobil-1 too, before I even rolled it off my cousin's driveway. No leaks.
You are perpetuating an old wives tale with no basis in fact.