Hello,
Now, I am using mobile 10W-40. I am in Jordan where the tempresture in the year between 3 to 30. So, do i have to use the recommended or is it enough?

 

You should follow the owner's manual, which, if I am not mistaken recommends either 0W-20 or 5W-20. Not sure if the car's made for other markets have different requirements. Check the owner's manual. That is your best reference

 

I am not sure how that converts from Fahrenheit temperatures, but 10W40 seems to heavy a weight of oil. Recommendations are 0W20 or 5W20. I think at the most I would use 5W30, sounds like the dealers use 5 or 10W30 a lot.

 

Since TCH does a lot of start up/shut down cycles, I would go with factory recommended oil. In US it is 0-5W20, so you should check your owner's manual. The idea is thinner oil will flow faster on start up and lubricate all parts sooner, also the engine may be designed for thinner oil which could affect lubrication with heavier oil. Your temperatures are pretty much similar to what we have in US South of 37F to 86F, except we could go bellow freezing for few days in winter and go way past 100F in summer, so I would be surprised if the recommended oil was much different. You also should get small MPG increase, possibly to offset higher price if such.

 

I agree with Pete. Also, the oil on these engines does not warm up and stay hot like a conventional engine. Oil circulation under these conditions (cold to intermediate oil temperatures and frequent starting and stopping of the engine) is very important. I'd stay with the 0 or 5W20 recommendations.

 

I just called my dealer and he recommend toyota full synthetic 5W-40 where it is the best for my country, please advice

 

Ask him for proof that 5W-40 is best for your country. Most likely, he's just selling what he has and not what Toyota recommends.

 

I heard of a couple dealers in California who were pushing 5w-30 a few years back before 0-20 was widely available. Also, 30 C is not terribly hot. We see near 40 here in the summer and I've always used 0w-20. If you can't find it locally, Amazon.com will ship a 6-pack to you.

 

The 0w oil has a higher film strength than the 5w full synthetic. I read this from a Mobile One web site a few years ago. Could be all the 0w synthetic oils have this same high film strength.

I have run the 0w-20 oil in my TCH from 5F up to 109F degrees with no problem.

 

I use only synthetic oil, 5W-20 in the summer and 0W-20 in the winter. It is getting hard to find a good price on 0W-20 here in the Indianapolis area. I found 15 qts. of Mobil1 0W-20 on clearance at Walmart and bought all of it. They now have 0W-20 Valvoline Synthetic and no Mobil1 0W-20. Almost $7 a quart now for 0W-20 now. They have several brands of 5W-20 synthetic, some in 5 qt. containers for $18.