Need opinions, please read post inside
 

After 2600 miles of breaking in the street port rebuilt by KDR using Redline synthetic oil. When I go get my first oil change, Dave at KDR ran out of the Redline oil and all he has at the time was mobil1 synthetic 10W-40. So I decided to go with the mobil1 sythethic. Do you recommend mobil1 for rotary and how is it compare to other leading brands. Is it OK to use 10W-40. What are your recommendations.

Synthetic??? In a rotary? It has been general rule of thumb that synthetics in a rotary is not neccesarily a good thing, as it gums up the plugs when it lubes the apex seals.

As for 10-40W, I used it exclusively in my 1st gen with no problems, but I didn't have to worry about turbos. I thought about it, if I was racing the care full time, I would go for the heavier weight. As it is a daily driver, I stick to 10-30W.

Go w/ a heavier oil in the summer and lighter in the winter. I guess it depends on where you live as well.

Get that synthetic out immediately! It can gum up your seals! Go to discount auto and buy 9 or 10 quarts of Valvoline 20/50VR1 SAE Racing motor oil. Its just as as cheap as normal oil but its probably the best for rotaries that is on the shelf. As you know your car takes 4.9 liters or 4 and 1/2 quarts for a change unless you have an R model(dual oil coolers it will take 5.4 liters you will have to figure out how many quarts that is). Drain the synthetic out and replace with new oil. Go on the interstate or somewhere you can get on it to flush out the rest synthetic. Run for at least 15 minutes. Then dump out that oil and replace again also changing the filter. Now you will be safe again! If you don't change your own oil just buy it and someone do the changes for you. Shame on Dave for that synthetic!!G.

Looks like we may be having the synthetic vs regular oil debate...

Lots of FD's have synthetic in the engines with no problems...thats not to say problems can arise. Many of the tuners for our cars will use synthetics.

synthetic oil in rotary
 

I have heard the debate on whether synthetic oil is OK in rotary engines before. Mazda does not recomend it- but they also have been wrong on other things re the RX-7. Main concern from the anti-synthetic camp is that as it is injected into the combustion chamber to lubricate, it creates more ash or residue when it burns. I wondered if this was in fact true, so I took four ounces of Mobil-1 and four ounces of Quaker State 10-30w and placed each in a cleaned pyrex glass watch glass (used for drying and evaporation studies by chemists and such). I then boiled the shirt out of each on my stove until there was just a residue left. Both looked like sh!t. I then took four ounces of each oil and mixed with four ounces of gasoline in two pyrex mixing bowls and set each on fire. (This I did outside. The smell from the first experiment was pretty bad, even with the exhaust fan going over the stove. Plus, I really did not want to light gas inside my house.)Again, both looked pretty bad after burning. The Quaker State residue was less "gummy" and could be broken into small flakes or pieces. Conclusion: who knows? I personally use regular non-synthetic oil, simply because changing every 2500 miles gets expensive with the synthetic stuff.
Ron A. 93 VR Touring, 90 BR GTUs

10W-40 is supposedly one of the worst weight combinations because there are more additives in it to stretch the weight out that far (from 10 to 40 over a temperature range) than any other weight range.

That being said, if you're using synthetic, you don't have to worry about it, because they don't have to add the same polymers to synthetic as they do to the dino-juice to spread out the weights.

You should be fine.

I agree - DON'T use 10-40, go with 10-30 or 20-50 conventional oil (Castrol GTX or Havoline SysIII are my choices 20-50 summer 10-30 winter)
Synthetics are wasted in a rotary - due to the high rate of combustion porducts contamination inherent in the rotary's design any oil needs to be changed at 3000 mile (or less) Intervals thus negating the primary advantage of synthics - long life