Donald we are always testing to see what works some people want to use synthetic (why is beyond me at $5.00 a quart for most synthetic oil and using it aa a rinse for a few thousand miles ) however now we can tell a synthetic user how to do an Auto-Rx cleaning.
Yeah, I'm still at a loss because even in oil munchers like my SAAB, a group III is perfectly capable of handling a clean/rinse routine. But it's good to see parameters for those who just insist. I know when I first got arx for my car, I had Mobil1 EP that I had just changed in. Everything seemed to work out okay....
I don't see anything special about regular GTX. I would put Pennzoil bulk, Super Tech dino from Wally World, and Haviland Dino as known good clean and rinse oils. Cheap oil for the short OCI's for cleaning and rinse.
For economy sake if I was hell bent on a full synthetic oil, I would do the cleaning on the back end of an oil change. I would log a bout 3000 miles on the full synthetic. Then I would change out the filter and add the cleaning dose of ARX. And run this combination up 2000 more miles. Now I have gotten the maximum value of the full synthetic oil and have run the ARX for 1500-2000 miles. Dump the sump and go for the rinse phase. In my mind running dino for 2000 miles is the cheaper, when compared to running a 3000 mile full synthetic rinse.
Let's face it new oil does not do any appreciable cleaning on its own, dino or full synthetic.
If you are dealing with seal leaks however, dino oil and ARX is a must. Read the application for seal leaks.
I have had good results with 5X30 Castrol both Dino and synthetic but Chrysler recommends Dino and with the 3oz maintenance dose of Auto-Rx it makes my engine happy.
What's the best weight oil for the clean and rinse phase? 5w30, 10w30, 10w40 thicker still? Or is it whatever oil viscosity is recommended by the manufacturer.
You should always use the manufacturer's recommendation as a starting point. A thicker oil will give you more oil pressure but less oil flow. I have a hunch that a thinner oil, which will offer better flow, would be beneficial for the rinse cycle.
What's the best weight oil for the clean and rinse phase? 5w30, 10w30, 10w40 thicker still? Or is it whatever oil viscosity is recommended by the manufacturer.
I would stay with a manufacturer recommended oil viscosity.