No, it's not an oil thread

[WuzzaCBXRider]

Has anyone (ever) heard of such a thing?

My Cadillac engine runs best on synthetic oil at startup and better on conventionals when hot, so I installed a 10 quart oil change pump and sump in the trunk. At loop changeover (160 degrees coolant) I exchange the engine oil on the fly - takes 45 seconds with a 12 volt aquarium pump and plastic tubing. As soon as that nasty synthetic leaves the engine it picks up 220 rpm and gets smoother. My gas mileage goes up 1.354 mpg, too.

 

[sixpack577]

Does the coolant temp not go up with the conventional oil?

 

[sixpack577]

Is the 220 rpm and 1.354 mpg increase consistant? Does it remain as long as the conventional is in use?
If not, is it just that the conventional oil was cooler? But then again, that would be thicker, and I would think it still would not be an improvement.
Where are the org engineers with the simple answer? So I can say, oh, and feel stupid for the day.

 

[mabupa]

Ive had issues in the past with a car burning more oil than usual on synthetic over regular oil, but I’ve never had any of my vehicles show a drop on MPG or rpms when running synthetic. Currently run amsoil on everything and the oil burner was traded in for another commuter. I’m assuming you are running exact same weight on both(?).

I blame it on Cadillac!!! Lol (can you tell I hate them after having to work on friend’s cadillacs?)

 

[WuzzaCBXRider]

I like my Caddy. On top of the hemi head Northstar small block is a sweet lil supercharger. What I can't believe is that exchanging oil 'on the fly' is actually possible (and) that it actually (efficiently) changes Dino oil from synthetic.