Why do people use 10W 30 oil when most manufactures call for 5W 30?

Question

What is the difference and does it matter?

Answer 1

it doesn't matter that much especially on that ,,there is very little difference in the twp,,the only difference is one is thinner than the other,,and it is recommended that you use a thinner oil in the winter months because cold oil is thick,,and takes longer to circulate,,but the difference in the two is barely noticeable,,both are good oils,,most people use a 30 weight after the vehicle get a few miles on it,,other wise..you can use either one,,and there is no harm that can be done by doing so,,i have been a t this for 35 yrs,,i hope this help,s.

Answer 2

They probably bought a case of it for a previous car before the car makers changed their requirements. If they are in an area where it doesn't get bitter cold the 5W isn't really needed since even 10W oil is not too thick, but car makers are trying to cover the needs of everyone across the country by hitting the worst case needs.

Answer 3

10 W 30 is what most of us grew up with and what weight oil you use can also depend on the climate and season. During the summer months in NE I run the lighter 5W, but in winter when you have a tendency to let cars heat up I would rather have 10W protecting me engine.

Answer 4

ive been playing around with old cars and motors for years. if its a new car use the recommended oil its as simple as that. if you put another weight in the motor chances are it wont hurt one thing .... i look at it like this though ... alot of the internal motor parts are oiled by "splash" so having the correct weight that the motor was designed for guarantees the oil will get where it is needed ... a thick gooy oil may not sling to where its supposed to especially if your sitting at idle in heavy traffic for extended periods ... i agree with the guy above that said the time to use a thicker oil is when a motor is getting older and has a few minor leaks and maybe is burning alittle oil .... the bottom line is to make sure you use a quality brand oil ... the speed at which an iol breaks down does vary by brand and personally ive come to the conclusion that valvoline oil stays the nicest for the longest ... and its my opinion that castrol is one of the worst for breaking down fast ... im scared of synthetic oil although ive heard it keeps its properties much longer than regular oil i worry about the effects it has on engine breakin and ring seal as well as being so slippery it can leak easier and maybe affect rubber seals ... contaminates get into the oil regardless and i would just rather change it every 3000 or so... if its looking dark its time ...

Answer 5

Stubborn people like me prefer the 10 weight upon warm up rather than the 5 because we disregard the closer tolerances and accuracy in today's machinery. It doesn't hurt the automobile. I personally get an uncomfortable feeling having very thin oil when the engine is cold for fear of excess wear. I like to have it thick enough to prevent any damage to the critical parts of the car. Just personal opinion.

Answer 6

Some people believe their personal opinion on motor oil make a difference. The wrong weight motor oil can burn up cams and more. In the summer it makes sense to run a heavier weight and in the winter run a lighter weight or if you have a high mileage vehicle with bad rings you could make do until it falls apart with a heavier weight motor oil.

Answer 7

Doesn't matter much..... they are both the same weight at operating temp..... just the 5w-30 gives better cold weather flow.... so less startup wear in the cold.... = a longer lasting engine.

Answer 8

Read the manual. on oil cap, my wife car says use 5-30, but manual says in summer time / hot weather 10-30 is recommended.

Answer 9

Because they don't read the car's owners manual. .. plus it's hard to find 5W-30 when you need it...
My car uses 5W-40 anyway...

Answer 10

I use 15w 40 instead. Too hot down south for light weight oil.