The subject says it all, this is in the southwest, where temps never drop below 25 (night) in winter and summers hit 100+ 3 months of the year. Is it okay to use 10w30 instead of the 5w30 mentioned in the manual ?
The 5W and 10W parts of the viscosity designation only apply at 0 degrees (centigrade = 32 degrees F). At 100 degrees (centigrade = 212 F), both 5W30 and 10W30 have virtually the same viscosity. Normal operating temperatures for engine oil are near 100 degrees, so as far as operating under normal conditions are concerned there is no advantage to 10W30 over 5W30. When the oils are cooler, both 5W30 and 10W30 will be more viscous than either is at
100 degrees. So, if you are worried that 5W30 is too "thin" you don't need to worry. At temperatures less than normal operating temperatures it is still ticker than either oil at normal operating temperatures. And when the engine is cold, it will circulate better than the 10W30 oil. As long as you are operating your car in an approved manner with the cooling system in good condition, the oil temperature should never get to much higher than 100 - 120 degrees (centigrade).Ten years ago, 10W30 was often recommended over 5W30 because of the worry that 5W30 would be more likely to break down because it required more viscosity improver to achieve the 5W rating. This has not proven to be a problem with good quality API certified motors oils that meet the latest classification. On the other hand, since you live in
I can see no reason to choose 5W30 over 10W30. If you are worried that the high temperatures may result in too low a viscosity when the engine is being stressed at high outside temperatures you might want to consider using a good quality synthetic oil. Newer Toyota are recommending 5W20 oil (as do newer Fords and newer Hondas). There is plenty of research that confirms that even 5W20 oil provides sufficient wear protection for modern engines, although I think everyone agrees the real reason for the thinner oil is improved fuel economy.
Ed
It'll be fine, but realise that if you do lots of short hops instead of long up-to-temp runs yuo'll increase engine wear a miniscule amount as 10w is more viscous at start than 5w so takes longer to reach the head. That said 5wt difference is bugger all.
Well, the reason wasn't that I wondered about gas mileage, it's more the fact that I have a stash of 10W30 sitting around from my other car and if I could use it in my friends mr2 I don't need to run out and buy 5w30.
Go ahead and use up the 10W30 and buy the manufacturer's recommended viscosity and grade in the future.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.