OK - kinda dumb - but WHY do all cars take 5 qts. of oil.

Think about it - everyone says - or the oil co's do (not the service manuals always) to change the oil at 3K. OK - that's all well and good - but why do much smaller 4 cyl. engines still take 5 qts.? Why should they be changed as frequently as a 5.0 V8 Stang? You get the point of my question.

1 - Why similar intervals with less cyl. that would create deposits, thermal breakdown, etc.

2 - Why still 5 qts. per car?

Seems to be should have correct ratio for all cars for the qts. like 1 qt. per certain amount of Liters displacement, etc., --- if the engines were designed that way - and the same change interval - say every 5K .....

Just curious


(Someone brought up in my botched subject post about RPMs higher in smaller engined cars - I agree, but that's certainly not always the case at all. THere are plenty of high reving high displacement cars out there, and low reving 4 cyl. engines too.) Maybe it's just the oil companies going with a happy amount to fill their pockets better - more than likey the case - but still - you'd think there would be more talk about this amoungst car people - some koind of 'inside' pseudo-equation to figure out, while althoguh all engines are baiscally made the same in that they take 5 qts. of oil - you can 'calcular' how ofteen to change your oil and filter based on the following input:

Oil type (Dyno, Blend, or Synth.)
Oil viscosity
Filter size
Filter quality (NOT FRAM CRAP, hah)
Engine Displacement
Engine Red-line RPM
Boosted or not
etc.

I think it would be an awesome (but time consuming) project to seriously do a little research, hard reasearch, about oil break-down times, etc., etc., etc. - all the hard science iinvolved and come up for a rough 'beta' versoin of some type of oil calculator.

Then with the calculator you could figure out what is the best oil and filter combination for protection, what is best for your dollar, etc.


Input?