I asked this:

and got this in response

and a closed thread.

-this did not answer my question.
-I'm not asking what type of oil is better or best.
-I've read 75% of the threads on that topic.
-I've heard people say on a few occasions "once you use synthetic you can't go back".
-I've also heard this is false.
-I want to know if one of the two previous owners of my car used synthetic oil for..let's say... 25 thousand miles....am I safe to go back to using conventional.

 

Oil is a sensitive topic and has been discussed to death on this forum. Many people run in fear or start wars over this...

To specifically answer your question:
Synthetic oil will mix fine with conventional... 5W20 oil is semi synthetic anyway.

 

Using syn versus dino oil doesn't coat or leave any type of benefit after you remove it to place in new oil. In other words it won't make a lick of difference switching your oil type if using the same weight between syn and dino, I did it all the time on previous vehicles and my 8 included.

It's the same worry people have on this as they do with blending different oil weights together when they have some left over; some fear it will make their engine explode

Get the idea?

That will answer the question you're asking. My question to you is outside of that question since you've read 75% of the topics involving oil, are you aware of the differences between the 2 when the engine uses oil by design?

Neither is designed for burning like a 2-stroke oil and syn burns slower than dino oil unless involving perhaps special blends that have additives to assist with this.

 

Always assume that the previous owner with 5w20.

At the current mileage, I wouldn't recommend synthetic. Go with 10w40 dino and add 4-6oz of Idemitsu premix to the fuel tank at each fill up. That's the safest way to go.

The consensus from the community is that 5w20 is far too thin and harms engine longevity.

 

I only run 0W00 oil in my 8 and it has been trouble free for 128,000 miles.

 

Sometimes I think the only consensus is that OIL harms engine longevity. Some say synthetic kills it, others say dino can't stand the heat, 5w-20 too thin, 10W-40 too thick...

Oil. Bad.

(kidding, kidding)

Flonker, a dealer once put synthetic into mine by mistake. I had them switch it back to normal oil, but naturally not every drop of synthetic was drained. It's been 10,000 miles or so now and it's still running fine.

 

would that be caster oil? lolol

 

noob thats baby oil lol

 

It's my special blend of man juice oil. It takes me a while to make 5 quart jugs.

 

but dont ya need lube to make that?

 

Yeah it all gets mixed together to make 0W00. It's a secret recipe.

 

I wouldn't be worried about topping off too much.
Running on 5w20 would scare the living hell out of me though.

 

I believe that this consensus of yours is geographically restricted to the southern USA and other hot climates.
My car has run on 5W20 and 5W30 Castrol GTX and is, as far as we can tell, in excellent shape at 85K miles. But then I live in Canada where the weather is generally cooler.

On the spectrum of viscosity, running too thick an oil will reduce oil flow during cold start ups and enable higher wear than a thinner oil. The oil pressure mod helps here.
Film strength drops with viscosity so you don't want to go to thin and risk oil break down.

Somewhere in between is the right answer... but only for your situation.

 

The EUDM manual states 5w30 for colder climates and 10w30 for hotter ones.
cST wise the difference between some 5w and 10w oils is minimal anyway. I wouldn't be too worried unless I had my *** freezing in canada
Even there i'd err on the safe side and use 5w30 at least though.

 

So why not just run 0w30, then.

 

I fixed it for you


and you got the exact respond u deserves.

and you start another one ? are you really that dumb ?

does it matter what the previous owner used? its ur car, u use whatever the F you want.

Is it really that hard to Goo-fuxking-gle something like this ? really.

your lack of common sense really ...

 

Here's a better idea:

Since you don't know what oil was used by your shop, or used previously by its past owners, why don't you pick an oil, any oil, with whatever weight you prefer, and use that from now on, and do an oil change right away, so that you KNOW what's in your car from now on?

Heck, do 2 quick oil changes with a 10 minute period of idling in neutral, and you will have the freshest supply of oil in your engine that you possibly can.

BC.

 

wow, u have a lot of man juice ... 5 quarts ? don't think most men can have that much ... not even in a 10+ years period ...

 

I think it's a disease on this forum once the topic of oil is bought up it eventually makes its way into the usual oil debates where most miss the main question the op posted.

He took what someone labeled as "once you go to syn, you don't go back" as a serious factual statement instead of realizing it was someone's oil preference of not going back to the original dino oil they used. No debate between using either or, no oil weight debate, nadda of that.

I think some are being a bit harsh on him when he's coming across as someone relatively new to the whole knowledge on engine oil and what not with a legit question I don't see often if hardly ever around here.

 

Hey man, if you already got an oil change you should be fine with what you have.

 

Personally for the last 88k miles my car has been running on 5w20. I also live in North carolina where the weather is typically warmer and humid. My car still runs like a champ. So much for being to thin. I think its a personal preferance really. As long as you stay within the paramaters that the mazda handbook tells you too, you should survive. I've never had any oil problems or engine problems at all. In fact my car runs like its still brand new, and the dealship at 80k miles when they did the last warrenty check up on it said it was in primo condition.

 

Yep, they run just fine right up until the time they do not run fine.

 

well i mean, thats just about any machine. One day it works one day it does not. Are you suggesting my oil is bad, sir? lol.

 

yeah I feel bad for starting what could have potentially been fatal for some here but so far it's been a mild thread.

Someone just gave me the impression that there was some rule that i never heard of that once you begin using synthetic, you have to continue using it. not as a matter or preference or opinion but that conventional could literally no longer be used.

doesn't seem like I have anything to worry about here then. Successful thread! This was not meant to be a "which is best?!!?" post I promise.

ty

 

you can use whatever you want, it's your car, it will not effect anyone's wallet other than your own.

I like the part u say as long as u stay within the parameters that the mazda handbook tells you too, you should survive. yeah, I know Mazda fuxked the PCM metering up, Fuxked the ignition timing up, fuxked the engine design up, and 2 oil nozzle point at corner, oh yeah, took them 7 years to fix some stuff in S2, and double oil pressure cuz E-mop and they know 5w20 is garbage and even 5w30 is not-so-great engine tear downs tells us that we are getting wear that even higher power 13B-REW don't have, cuz of our lovely 5w20. yeaaaaa

and dealership ? ... ok, some don't even know how to use that damn compression tester, wrote the test at whatever rpm it was, when there is a poor 250 rpm button on the front of the tester ... yeaaa

again, it's ur car, u can use whatever u want, just don't cry when your engine goes low compression and nothing is usable cuz everything is worn beyond copper ... enjoy