in most forums i have read when they are trying to infer base stock composition they do it by reading flash point or pour point specs.and most of them use older mobil 1 esp formula 5-30 and its current reformation , the new one mobil esp 5-30.and they are many because that oil had a lot of fans,thats why i used the ''big example''.
they just thought that older one had same base stock with new one only with less esters.
how for me to know that? mobil does not mention it anywhere.in all the other bmw forums i follow nobody mention anything about that. perhaps nobody got that deep as much as you do. we know that shell is gtl based bcs there was an announcement but for mobil no reference..
anyway first time i hear about altitude and oil.
ok, then why oil companies and some very legit sites post that ambient temps relate with engine oils?
Synthetic oil is a lubricant made up of artificially made chemical compounds. Read about how synthetic oil compares with conventional oil and more.
www.machinerylubrication.com
When Synthetics Always Makes Sense
Towing and high loads. Slow speed, high load (e.g. towing), long hills, high-mileage engine, long oil service-interval, and
high ambient
temperatures are the worst-case scenarios. It's in these cases that oil films get extremely thin and high wear rates can ensue. This can be offset using premium synthetics with the best additive packages.
www.totalparco.com.pk
When should I use 5w30 oil?
You should always use the oil recommended by your vehicle’s manufacturer. However, 5w30 oil can function in temperatures as low as -30ºC
and as high as 40ºC, making it an ideal choice if you drive your car in a place with relatively
high seasonal temperature variations.
In this guide, we look at the impact heat can have on cars, and what can be done about it.
www.holtsauto.com
Cooling systems rely on coolant/antifreeze to keep all parts of the engine cool.
On a hot day, this liquid runs around the engine at a higher temperature, causing some parts of the engine to overheat and fail.
in first page on my post #18 i have a map like many you can find online that relate ambient temps to engine oil temp.why ?