I have searched and did not find the question so I wanted to ask. I have a 2010 Mazda 3 it only has 26K miles on it. I just let my friend change the oil for me, I done some floor work for him so he wanted to pay me back with a couple of oil changes. He used 4 quarts 10W30 AMSOIL and a for the the half quart he used half a quart of lucas oil stabilizer he had around the garage. Is this oil going to be too thick? I usually use 10W30 so I am not worried about that. I am staying all summer in Florida and I know with hotter weather higher viscosity are better, but can a Mazda 3 run okay on higher viscosity oil if the Lucas changes the oil to a 10W40 or higher? What would half a quart or Lucas change oil to also?

 

Anyone?

 

Andy, I don't think you need to worry. That amounts to about 11% of high viscosity oil in your standard multivisc oil. If there is any disadvantage it would be higher pressure in the oil pump at low temperatures. For high temperatures you have a little more protection.

for next time ask your friend to hold off on the stabilizer. He can use it on some high mileage engines that have some wear on the inner parts.

 

Isn't genuine mazda petrol oil 5w30?

 

I don't think the stabilizer will thicken the engine oil, so your oil will not become 10W40 or higher. What AMSOIL oil you used? If you used their signature series (100% synthetic), I don't think you need to add any stabilizer

 

My owners manual states 5w-20 for all but the most brutal conditions. I've been running 5w-20 full synthetic since 19k miles in Texas heat with no issues. It's 104* right now but earlier this week it was up to 108*!!
The thicker oil should not be used in colder conditions, but "can" be used when its over 100*. Your mileage may suffer a little bit though.
Thicker is not better with modern engines. Machining has reached a point where tolorences are tighter than they used to be in production engines. Thicker oil simply means you will be running "dry" for a longer period of time during start up. Dry running equals more/greater wear in the long run.

 

Synthetic oil is more free flowing. My car calls for 5W20 oil but in the summer I use 50% 5W20, and 50% 10W30. In winter i use 5W20. I use Amsoil synthetic oil. so my oil is 5W10W20W30!