I have adressed this question on many adresses, but never got a really
good answer. My car is Elantra 1.6 liter, model 2003, with hydraulic
valve lifters.
I would like to use fully sinthetic oil, but there is a catch. I live
in Croatia, and for our climate (up to 36°, sometimes 40° Celsius in
summer), manual (and hyundaiwebtech) recomends 10W40 gradation oil,
but fully sint. oils come only in gradation 5W40 or 5W50 (and other
not relevant here). Diagram in the manual shows that 5W40 is good only
up to 20° Celsius, and 10W40 goes to 40 and more.
Is it true that semi-synt 10W40 is better for hot climate than full
synt 5W40? and if so, can I use 5W50 instead (it is not mentioned at
all in that diagram)?
The reason for abandoning 10W oil is because there is quite lot of
lifter tapping untill engine is warm, and I am hoping to improve that
with synt oil.

 

5W40 and 5W50 are weights that aren't typically used here in the U.S.
Realistically, I think you should be able to use the 5W40 without a
problem, but I also don't have good data to peruse. You could try to look
around the web for other viscosity and usage charts.

40C is not very different from the warmer areas in the US climates, and
many automakers specify 5W30 in all US vehicles. This is why I think
you'd have little problem with 5W40.

I don't actually know enough about the synthetics and semisynthetics to
speak on the differences between them (or regular motor oils).

 

> 40C is not very different from the warmer areas in the US climates, and
> many automakers specify 5W30 in all US vehicles. This is why I think
> you'd have little problem with 5W40.
>
Yes, I noticed that, same cars, same climate conditions, even the same
viscosity chart in my manual as on Hyundai webtech site, and yet
different viscosity is used. Interesting!
Anyway, thanks for the info!