Okay, so, I got my oil changed today. I told the man I needed 5W20 nonsynthetic per Mazda's recommendation. He said ok, so I walked away and made a phone call. This guy changed my oil last time as well, so I figured everything would be alright. I pay for the oil change, get my reciept and go. When I get back, I look at the receipt and realize he put 10W30 into the car. I was none too happy at this point, but they were closed when I called. I'm going to go back tomorrow and ask them to drain my oil, refill with 5W20 and then replace the filter. Is driving around with 10W30 a bad thing? I'm not oil savvy in the least. Do you think they'll change it this time for free?

 

i would get it changed but it wont make to much of a difference, esp for a day or 2....its a little thicker so it might be a little slow to move thru the oil coolers, but since its not to cold out now, its not a big deal.

Id get it fixed, but its nothing to worry about, IMO.

Im running 5w30 cause its easyer to get in the brand/grade of oil i use.

 

I think Europe uses 10-30w

 

Really it comes down to temperature ranges. In the summer, I run 20w-50 now. Still use the 5w20 in the winter. See the ranges in your manual, and it will tell you the various viscosities that are acceptable based on temperature.

 

Unlike the rest of the world, the US does not give owners the grade scale... so all they recommend, summer in NV or winter in MN, is 5W-20 non-synthetic. But, 10W30 is actually fine before winter hits, so no point changing it. If the guys are lazy, they'll tell you the receipt is wrong and that you have the correct oil. I wouldn't bother change it just yet, unless you do not drive enough to change it again before snow hits.

 

10w-30 isn't excessively thicker then 5w-20's. You'll be fine...you might notice a very slight effect in mileage/power. Running 0w-30 would actually probably be a nice oil choice for those who haven't read much about changing oil technology and are overly paranoid about thinner oils.

 

i ran the mobil 1 0w30 in my miata, did lots of track use, it had an upgraded radiator and a 4"x8" oil cooler and only had a 4.5 qt system, it ran great, and the oil (at 3000k changes) held up well even under a lot of stress from track and daily driving.

 

I have been running 20w-50 Amsoil synthetic since middle of March since turbo was installed with no problem. I will switch to 10w-40 Amsoil synthetic in the winter to help make sure there are no starting problems.

 

Just remember that too thick an oil can be just as bad as using too thin an oil for an application.

Viscosity is NOT a measure of protection!
http://www.bobistheoilguy.com

UOA's will tell you if your thick oil regime is doing anything other then sucking power and mileage.

http://www.blackstone-labs.com
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Here's a good thread on viscosity as it relates to engine wear.
http://theoildrop.server101.com/cgi/...127;p=2#000047