jgoldstein2000

Ok... this is embarrasing. Instead of adding 5w-20 I put in 20W-50. I know... I'm an idiot but I was in a rush and wasn't paying attention. I haven't driven it yet since I added the oil because I am not sure how big a deal this is. I don't know much about engine oil. Can someone explain to me the differences and if I drive the car now whether I will hurt my 8. Thanks....

Sincerely,

idiot

Jsuzuki

It probably will not hurt the car short term. Your fuel mileage may go down. I would go do another oil change with the correct weight oil. The 20w-50 remaining (in the oil coolers) and stuff won't adversely affect engine life.

If you really want to know what the numbers do, go do a google search. There a good resources out there on the interweb...

Racer X-8

Yeah, just drain & re-fill with 5-20. Your new filter will be ok too.
You could use the collected 20-50 in another car maybe.

jgoldstein2000

Unfortunately I don't know how to drain my oil myself so I would have to bring it in for a change.

I just called the dealership and the service guy I talked to said he thouught it would be fine to leave it as is, that the 5w-20 I had in there will mix fine with the 20w-50 I added (about a quart). He sais I might get worse gas milage but that was about it.

Do you agree with this statement?

RotorManiac

No, I wouldn't keep it. The whole procedure is very simple. Even at a gas station you can have the oil changed in a matter of minutes! And the cost is rediculous, at least in my country it wouldn't set me back for more than 30-40euros. Why risk it then?

Racer X-8

Oh, I thought you did an oil change. Silly me...

One quart, huh? I think I agree with the service guy. You must be close to an oil change anyway, right? If you needed a whole quart to top it up, it's been a while, hasn't it? I would change it pretty soon myself - couldn't stand the thought for very long...

jgoldstein2000

I am wondering if I put too much in? I was down to a little above the low line... I thought a quart was about right. I only have about 900 miles on the car...

Racer X-8

Well? Don't wonder about it - check it again. I think you over-filled it. Come back after you can tell us how high it is on the dipstick now...

jgoldstein2000

Just a little too high - half way between the full line and the top of the range. Hope that is ok.

jgoldstein2000

Racer,

Thanks for your responses. Do you think it is ok?

sandia8

ONE QUART WILL PROBABLY NOT AFFECT THE ROTARY
SINCE IT WILL BE DELUTED , EVEN BY THE 20W THAT WAS IN THE 20W-50

BUT IF YOU WANT TO BE SURE YOU CULD CHANGE IT
ALSO YOU MIGHT CHECK THE DIPSTICK, UNLESS IT IS LIKE AS THICK AS MUD YOU WON'T HAVE AN ISSUE

BESIDES TOO MANY OWNERS ARE FREAKING OUT ABOUT THEIR OIL - YOUR 8 SHOULD USE ABOUT 1 QUART IN 2000-3000 MILES, THATS NORMAL, NO BIG DEAL, JUST KEEP AN EYE ON IT, NO NEED TO CONSTANLY ADD MORE OIL TO KEEP IT AT 100% FULL, BETWEEN THE MARKS IS FINE.
now if you get close to being a quart low, THEN don't plan and drive a long highway road trip without adding some oil, but a few miles aroung town is not an issue

gsdev

Don't drive your car with 20W50 in it!!!!!!
Drain it and replace with 5W20!
The oil injectors are designed for very thin oil.
20W50 is some of the thickest oil you can buy, 5W20 is the thinnest. You will %$#@ up your engine. It may cut your rotor and could possible screw up your oil injectors.

Racer X-8

Ok, I had to go look at my dipstick to see what you meant about "end of the range". hehe Where it goes from flat to round, right?

That's not way too much. A lot of mazda joints do that intentionally, cuz they know it uses oil & it stands less of a chance of going too low before they see it again, I think that's why anyway...

I think you'll be ok.

jgoldstein2000

Wow! That's pretty scary. I guess I will call the dealership tomorrow and see if they can do an oil change for me.

Why is it do you think that the service department at the dealership and the 2 gas stations I just went to (neither did oil changes with 5w-20) said it was no big deal? I told all of them I was worried about it and they all told me to relax. Now the gas stations... that doen't suprise me as they don't know much about the rotary... but if the mazda service guy said I was fine I am really suprised to hear your dire prognosis.

I will have to drive the car to get it to the dealer tomorrow if I want to do an oil change. What do you think about driving 25 miles to get there?

gsdev

I asked a Mazda engineer about using 5W30 (not too much different than 5W20) and the metaphore he used was the difference between KY and Vaseline with sand in it. The viscosity can cause extra friction between the rotor and the housing. Also can gunk your oil injectors (specific to rotary). If you drive it, keep an eye on your oil pressure. If it goes up much or if it drops, stop the engine. I didn't mean to freak you out, but if I had the opportunity to #^@% up my car, I would want someone to get my attention.

stickman

One quart out of around 6 is no big deal, that is why the service people have told you it is no big deal. I have been driving and working on my own cars for 35 years and have owned many different cars at least six of which have been sports cars. Even if you did an oil change you would only have changed around 3.5 quarts as the rest is in the oil coolers and lines. Don't sweat it, you have plenty of 5-20 in there compared to the 20-50.

jgoldstein2000

Thankyou Stickman and GSDEV and everyone else. It doesn't sound like I have much to worry about but I might just change the oil tomorrow to be on the safe side.

Racer X-8

I would just like to mention that the oil pressure gage is actually digital. Yes, it looks analog, but it's either at zero, or a tad above the center of its sweep. The gage needle will point nowhere else, cuz it's not analog.

So, you will not see any over-pressures, and if you see it go to zero, you're in big trouble.

Having said that, you will not have a problem in taking it somewhere to have the oil changed. I still think it would be ok as-is. Go ahead and have it changed though, if it will give you peace of mind. Then buy a case of 5-20 oil. Keep one in your car if you go on a long trip. It's a little rare to find, especially at gas stations.

sandia8

Rotary engines burn more oil than pistons engine. Fact.

Carry a spare quart in your trunk!

In my view, Mazda wants owners to check the oil every 2 fill-ups NOT because the 8 will need oil, but to get owners ‘in the habit’ of checking and thinking about their oil level.
Something they did not have to do with non rotary engines. So Mazda gives you a dipstick and a low oil warning light.
Common sense, keep it between low and full and do not be obsessive compulsive about it. Overfilling is worse next to running out totally. You would probably need to be 2 quarts low and racing the engine to cause any real harm.
You have TPM’s, but you still need to be mindful and check your tire pressure regularly.
After a few thousand miles of checking, you will be able to know almost exactly when you will need to add oil in the future without checking it every 2 fill ups.

In my old RX-7 it would be exactly 1 quart low at 3000 miles, and that is when I did a full oil change anyway. Never varied for 140,000 miles of driving. So I did not check my oil at all unless I was about to take a long trip that would exceed my 3000 mile limit.

zoom44

re-read what racer x-8 just wrote and you'll know what i think to. your fine but changing it might gve you peace of mind. dont panic tho.

SpinninAgain!

Fact #1
The flat area of the dipstick between the low mark and the high mark represents 1.7 US quarts. It's in your owner's manual.

Conclusion #1
If you were near the low mark and added 1 qt then you should now be between the halfway point and the high mark. IOW, you're fine as far as how much oil you've got.

Recommendation #1
Check the dipstick to be sure.

---
Fact #2
The oil capacity is ~7.5 qts including the coolers. You were down ~1.5 qts, so you had ~6 qts. You now have ~6 qts of 5W-20 + 1 qt of 20W-50.

Conclusion #2
Assuming the two oils mix thoroughly in the system after a little running, and assuming the net viscosities will be an average of the combined oils, you will soon have ~7 qts of 7.14W-24.29. I'm no engineer so I don't know if those assumptions are true.

Recommendation #2
If Conclusion #2 is technically correct, then 7W-24 seems pretty close to 5W-20. I wouldn't worry about it, especially in a warmer climate and time of year. Top up when necessary with 5W-20 to continue diluting the oil back toward where it should be. Change oil & filter at your regular interval. RELAX.

---
Question to the experts #1
Are the two assumptions in conclusion #2 valid?

Racer X-8

If you're concerned with dynamic viscosity, you'll have to re-calculate using centistokes.

But, yeah, you're close enuf.

gsdev

If you have 6 buckets of sand and 1 bucket of rocks, the two won't average. This is my understanding of how oil works.

Racer X-8

Oh, I don't think it's like that. I did a quick websearch for fun, wasn't plentiful in results, but here's a pretty good one...

http://www.sweetspotbikes.com/mixoil.html

Sand & rocks. Reminds me of the old anology of solutions .vs. mixtures. The sand goes between the rocks, so the combined volume doesn't change from that of the rocks alone, much like that of molecules in a solution...

But, anyway...

sandia8

I have had 2 different oil viscosities in my car(s) before.
They mixed as far as I could see, and I never changed oil and saw it clumped or chummed. But I am not an automotive engineer.
Also I understand that the oil will be getting diluted and broken down by any contact with the gasoline that seeps past into the oil.