Hi folks,
First time poster here. I searched all over the internet but it seems I'm the first one to ask this very specific question:
It's clear that all other things being equal, a lower "W" rating is preferable (e.g. 0w-40 better than 15w-40). However, almost all information refers to places where temps drop significantly in winter. So, what about tropical countries which have basically constant temps all year? Where I live a "cold" start is at worse done at 15 Celsius (59 F) but the average start is probably closer to 25 C (75+ F), where the advantages of a lower "W" rating are perhaps not that significant. This is made more complicated for the fact that wider range multigrades are sometimes harder to find or considerably more expensive.
I found this table (not sure how accurate) which shows how viscosity behaves at specific temps and after 20-25 C is basically a wash, mostly so if you look at the 10w-30 and 5w-30 lines (same hot viscosity):
Reference: https://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm
Some folks around here argue that using too high of a W rating here is risking engine damage. My counterargument is that the money/effort spent in searching for that lower W rating is not worth it vs simply buying a good quality oil which has better properties protecting from cold starts via baked-in additives or simply better engineering.
Is my reasoning wrong? Down here the standard (for better or worse) is 20W-50 and I bet most cars 5+ years old get it as default (think of it as the 30psi tire pressure). You don't see those engines blowing to pieces or needing a rebuild constantly so I'm really curious as to whether or not that extreme 20W oil is actually not too bad for the local conditions (of course leaving the 50 grade out).
First time poster here. I searched all over the internet but it seems I'm the first one to ask this very specific question:
It's clear that all other things being equal, a lower "W" rating is preferable (e.g. 0w-40 better than 15w-40). However, almost all information refers to places where temps drop significantly in winter. So, what about tropical countries which have basically constant temps all year? Where I live a "cold" start is at worse done at 15 Celsius (59 F) but the average start is probably closer to 25 C (75+ F), where the advantages of a lower "W" rating are perhaps not that significant. This is made more complicated for the fact that wider range multigrades are sometimes harder to find or considerably more expensive.
I found this table (not sure how accurate) which shows how viscosity behaves at specific temps and after 20-25 C is basically a wash, mostly so if you look at the 10w-30 and 5w-30 lines (same hot viscosity):
Reference: https://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm
Some folks around here argue that using too high of a W rating here is risking engine damage. My counterargument is that the money/effort spent in searching for that lower W rating is not worth it vs simply buying a good quality oil which has better properties protecting from cold starts via baked-in additives or simply better engineering.
Is my reasoning wrong? Down here the standard (for better or worse) is 20W-50 and I bet most cars 5+ years old get it as default (think of it as the 30psi tire pressure). You don't see those engines blowing to pieces or needing a rebuild constantly so I'm really curious as to whether or not that extreme 20W oil is actually not too bad for the local conditions (of course leaving the 50 grade out).