What if I have mixed 5W30 and 10W40 motor oils?

I checked my oil level just before a trip and noticed it was low. I put in a 10W40 oil. Since I added this oil my idling has been off (fluctuating). I checked the oil used in my last oil change and it was 5W30.


Could the change in viscosity be messing up my idling?What if I have mixed 5W30 and 10W40 motor oils?
You would have 71/2W35 ....





it shouldn't have any effect on the idling ..





if your oil was low, you may not have had service done recently so you might need a tune up also ..What if I have mixed 5W30 and 10W40 motor oils?
I don't think it will hurt anything long term BUT... to be honest, mixing oils like this... is just not recommended. They just don't blend together very well. The molecules are different. I always keep the same oil on hand that matches the oil I run. It's a good habit to keep 1 or 2 quarts in the trunk for just such a need.





I would change the oil ASAP and let this be a lesson for you.... Don't mix oils that don't match weight and don't mix synthetics with regular oils either.





Will it hurt the engine? I don't think so but it's not good for the oil. The better oil will be degraded by the lesser oil. In a pinch, it's OK but driving a car one quart low won't hurt a engine till you get the right oil to match. Now the oil should be changed even if it was not up for a change. It's a waste.





Everything you need to know is here:





http://www.knizefamily.net/minimopar/oil鈥?/a>
yes drain all the oil right now leaving it in there will cause severe engine damage
nah
nuthing wrong with it you just better use right oil next time
It won't change the idle, just change the oil when you have time.
Depends what engine you have


ford zetec recommend 5w30


any thicker oil will cause misfunction of the hydraulic lifters


I:E bad idling


suggest you change your oil and filter
It shouldn't mess up your idling. There is a article talking about oil viscosities and what they really mean at this site:http://members.rennlist.com/oil/Motor%20鈥?/a>
Last time I checked the difference in oil didn't mess up the timing of a car. It could mess with the oil pump, though unlikely. The pump is designed to handle only the specified oil the engine was built to run with. The bad idling sounds like a bad distributor cap, ignition coil, or distributor rotor. Hope this helps.