Hello,
I have been pondering this for a while, spending money on Auto Rx (even tough I believe it is great) is not in my case an option I would like instead try Delvac 1 5W-40 in mmum's 3.1 V6 with 209,000km or 193,000 miles. Since it is ester based and has got TBN of 12 it should do a good job of cleaning the engine. The engine has been properly maintained with mostly dino oils,it had been filled with M1 10W-30 3 times in its life and twice with Pennzoil Performax. It is relatively clean and has no leaks , but I can see looking dowm oil fill hole some varnish that I can scrape of with my finger nail.
I have been pondering this for a while, spending money on Auto Rx (even tough I believe it is great) is not in my case an option I would like instead try Delvac 1 5W-40 in mmum's 3.1 V6 with 209,000km or 193,000 miles. Since it is ester based and has got TBN of 12 it should do a good job of cleaning the engine. The engine has been properly maintained with mostly dino oils,it had been filled with M1 10W-30 3 times in its life and twice with Pennzoil Performax. It is relatively clean and has no leaks , but I can see looking dowm oil fill hole some varnish that I can scrape of with my finger nail.