Here’s a couple data points for you from my 2005 Honda Odyssey. 212k on the clock. The engine is *heavily varnished. Or should I say— was.
I switched to VRP last summer.
Last August after about 1000 miles on VRP:
View attachment 261824
A month later:
View attachment 261825
Changed the oil just before Christmas. This is now the second fill of VRP:
View attachment 261826
So after just one drain of VRP and about 1000 miles into the 2nd drain, I’m already seeing considerable cleaning in an area of the engine that see very little oil flow and is notoriously hard to clean— the rocker arms. The external surface is not directly oil-wetted, yet VRP is removing some VERY heavy varnish.