Subaru manual recommends 5w-30 but also states "Engine oil viscosity (thickness) affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot
weather, oil of higher viscosity is required to properly lubricate the engine."
That being said they list 5w-40 as also acceptable in the -40 to 50 Celsius range (-30 F to 110 F range). Other oils listed are 10w-30 10w-40, 10w-50 for -20 C (0F)to 100+ range.
Question, I've been running 5w-30 PU since November in northeast PA, mild winter. Summer can hit 90-100F easily, especially in July and August. Would I benefit from a 5w-40 and/or any of the 10 weight oils listed in the manual? And by benefit I mean better protection for engine in hot weather. I only put 400 miles a month on the car, will be taking a 560 mile highway trip in early Sept. probably 80% city miles normally.
My understanding was that with liquid cooled engines the need for "heavier" oils in hot weather was negated, according to Bob's Oil U lesson 2 or 3 I believe. If so why did Subaru put that in the manual?
weather, oil of higher viscosity is required to properly lubricate the engine."
That being said they list 5w-40 as also acceptable in the -40 to 50 Celsius range (-30 F to 110 F range). Other oils listed are 10w-30 10w-40, 10w-50 for -20 C (0F)to 100+ range.
Question, I've been running 5w-30 PU since November in northeast PA, mild winter. Summer can hit 90-100F easily, especially in July and August. Would I benefit from a 5w-40 and/or any of the 10 weight oils listed in the manual? And by benefit I mean better protection for engine in hot weather. I only put 400 miles a month on the car, will be taking a 560 mile highway trip in early Sept. probably 80% city miles normally.
My understanding was that with liquid cooled engines the need for "heavier" oils in hot weather was negated, according to Bob's Oil U lesson 2 or 3 I believe. If so why did Subaru put that in the manual?
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