I was just wondering, which is best for my '81 GSL? Synthetic oil or just plain old regular oil?

 

This is gonna stir up another raucus around here...
Look in the first gen faq, thats the closest answer you're gonna get.

Some say synthetics kills rotaries, some don't, but since a rotary consumes oil with regular driving, I say why spend more when traditional oils work fine.

Here, just read this http://www.mazdatrix.com/faq/synthetc.htm

 

I'm sure everyone will first say to search the forum on this, but I'll try to briefly answer here.

First and foremost, you have an oil metering pump that is mixing small amounts of engine oil with your fuel mixture. For this reason it might be ideal to stick with regular oil, seeing as how synthetics usually don't burn as cleanly. They can also cause other problems (search the forum).

Some people use synthetics anyway, I think Redline is one that people use and it burns OK. Ideally, if you want to use them you should remove/disable the OMP and start premixing 2-cycle oil in when you get gas (something like 1 oz. of oil to every gallon of gas). That's pretty much what I'm doing right now, and it works like a charm. Hope this gets you started.

 

My 2 cents on the subject. Tradition motor oil works just fine. I had a 79 go 284K on castrol 20\50. If you want the ultimate in protection for your engine then I would remove the metering oil pump and premix good 2 cycle oil with your gas and then use sythetic in the engine. If there is no metering oil pump the the engine oil is not being burned. But personally I think this is overkill for a normal daily driver. If you are someone who redlines the engine everytime you run through the gears and drive like you are racing all the time then maybe you should consider this procedure otherwise, I would use plain motor oil and be sure to change it every 3k miles without fail. But again, that is just my 2 cents on the subject.

 

My car has had snythetic oil used in it until I bought it just over 3 years ago (It's an 84 GSL) There "seemed" to be no adverse effects from using it. Mind you, my rotor housings could be clogged up or something. But, all in all. the car ran great when I got it and ever since I changed over to traditional oil, it's been working just as good. But, I did switch to regular oil because the mazda dealership recommended it.

 

Ok, heres how it goes. REGULAR motor oil for the engine and synthetic for the tranny and rear end. I've heard that redline gear oil works very well for the tranny and rear end. Any regular non synthetic is good for the engine.

 

what about "royal purple" sunthetic oil?