I dunno about you guys but i found that manuals are usually correct. Usually there is a chart for engine oil usage. For example, a new car uses 10/30, after 2 years use 10/40 or 15/40, after 5 years use 20/50. After 6 or 7 years overhauls engine and use back 10/30. How hard is that?
I often wonder why we are brainwashing ourselves with brands, when we could just use recommended viscocity from any brands?
Of course its quite silly to use 20/50 for new cars, because everything would go wrong.
And synthetics are the best. Even better are those blended with Esters. New synthetics would work right up to 10K. No need to change every 5K. Even the new car manuals already stated this.
For K cars, its best to stick to lighter oils like 5/30 or 10/30. I remember it can go up to 15/40 and not more. Because the small high reving engine cannot produce maximum power with thicker oils. My mechanic uses 10/40 for his 15 year old kancil, because it is burning engine oil with 10/30. But its logical.
Like you try to swim in water(10/30) and mud(20/50).
