Engine oil for a hot summer

[old man emu]

Here's a question that someone from the south-west USA might be able to answer.

During summer, the air temperatures where I live in Australia can sit between 32C (90F) and 40C (110) for several months. The recommended grade of oil in all the books is 50. I was thinking that next summer I might change to 70 grade.

My WLA is my daily ride, and I can easily clock up 250 miles per week in runs of 25 miles. A lot of this distance is done at 50 - 55 mph, with frequent stops at traffic lights. The engine is in good tune, with the mixture just about perfect (or it will be when I get the idle mixture checked by someone who is not ham-fisted like me).

What is the general opinion on switching from 50 to 70 for the hot weather?

By the way, I'm using Phillips 100AW aviation oil which has an anti-wear additive approved by the USA FAA. If I was to go to 70 grade, I would be using Phillips 120AW. Both oils are mineral oils.

Old Man Emu

[Bigincher]

The problem with heavier oil is when it's cold. Oh sure, it might circulate just fine after it heats up, but the motor will suffer from poor circulation on initial fire-up when it's cold. I went through my "70-wt phase" decades ago when I thought Kendal 70 racing oil was thee shit! I soon discovered it's just too thick.
You'd be much better served using 60-wt in hot climate.

[doc9339]

I agree 70 is to much. Look at the recommended weight in a FSM: Go with that. Remember, the WLA was made for tough seasons, cold, warm or super hot. The manual has recommendations for each type of weather

[Pascal]

Back in the war years, the WLA rode in cold russian tundras and in festering hot egyptian desserts..
And after all these years, more than 10% of total production is still on the road, eating miles on ordinairy 50 wt..

[59Panman]

I am running Valvoline VR1 Racing 60wt. conventional oil. I likeee!

[bangkokbob]

Hi.
I use 60wt Amsoil synthetic all year round here in Western Australia.
No problem just a bit harder to kick in winter.