LubeDude
Admiral
- Joined
- Oct 8, 2003
- Messages
- 6,945
Well, I know some of you know that the wife drives an 87 Mazda RX/7 rotary engine with about 285,000 miles on it. Well, I have normally used Dello 400 15W-40 oil in it nearly the whole time we have owned it since about 100,000 miles, so that means we put about 170,000 miles on the car ourselves. Well, to get to the point, I have been told "NOT" to use Synthetic oil in a rotary, So, being the person that I am, I changed it over to Mobil 1 about 5,000 miles ago. This car eats plugs like I change shorts, so I was hoping that since synthetics do not have much in the way of an ash content that they may run a lot cleaner. So, I do an oil change last weekend at 5,000, and the plugs were cleaned when I changed the oil to the Mobil 1, they had about 3,000 miles on them at that time, well, they normally need changing about every 8-10,000 miles anyway, so I took them out to have a look see. They were indeed worn out, but to my surprise, they were really carboned up badly, worse that they were with the dello 400. Really surprised me. These engines have an oil injection system that injects sump oil right into the rotors. No adjustment on the oil pump. It does run very rich though, but Im still surprised at the amount of carbon I found.<br /><br />This oil isnt actually designed as a twostroke type oil, so it has no bearing on an outboard with synthetics, Ive been very satisfied using synthetics in them and the car runs great other that the deposits I found on the plugs.
