Differences of opinion (Oil Related)

[97BlackX5.0]

Okay I know there are differences of opinion on oil types and synthetic vs non synthetic... my question is on the viscositys... many people believe that using thicker oil helps the engine last longer... is there any truth to this... I worked for an auto parts store for about three months and many people would come in and ask for a filter for there almost brand new car 02-03 and then ask for 10-40 or 15-50 to go in it... why would someone do this to a brand new car.... i know that cars are going with thinner and thinnner oil to pick up mileage but also know that clearances in the motor are getting tighter and that they can do this without problems. Our expedition runs 5-20 part synth... i cant imagine someone putting 10-40 in it.... is there some reason they do this other than (thats what they learned when they had older vehicles). I run 5-30 synth in mine year round and have 133k on my truck... I'm not attempting to flame anyone with this post just trying to figure out what your line of reasoning is for putting heavy oil into a machine that neither requires it and could possibly hurt it...

 

[huskyfan23]

Increased oil pressure?

 

[aldive]

There is NO reason to use 10w40 in your Explorer.

I live in hot Florida and use Amsoil 0w30 in my 99; it has 100k miles on it.

 

[Rhett]

I'd say, for most newer vehicles, those people putting 10-50 in a new vehicle don't need to be doing that.

Now for older vehicles with worn rings, and so forth, 10-40 or 10-50 might be ok.
For a 500 hp engine, 10-40 or 10-50 might be ok. But for a newer vehicle? Shouldn't be necessary.

 

[DeRocha]

I use Mobil1 5w30 and 10w30 in my X and have 130K. I can only assume people are using 10w40 based on the acceptable oil chart in the owner's manual and that is what the are used to buying.

IMO once an engine is running synthetics are the best. However since most engine wear occurs during start up I often wonder about vehicles (Post office trucks etc) that go through many stop/start cycles per day.. I would think synthetic and less viscous oils would drain back into the pan faster than non synthetics / more viscous oils. So depending upon the time between starts & stops thicker / non synthetic oils could still be coating engine components during start up when thinner synthetics are still in the pan. Obviously during a complete cold start the synthetic / thinner oils will reach the vital engine components faster.

 

[Bronco638]

In addition to DeRocha's post, I recall seeing an on-line article that stated that a large delta (difference) between the cold and the hot viscosity ratings was not good. That is, it's better to use 10w30 than 10w50. If you want a high hot viscosity (for whatever reason), go 20w50. Given the tight specs that today's engines use, it's best to go with manufacturer's recommendations. Having an engine try to pump thicker oil just wastes energy (that could be better put to use moving the vehicle!).

Just my $0.02.

 

[F14CRAZY]

Derocha: I never thought of that. Seems to make sense though. I figured a thinner oil (like 5/30) would be best when starting up because it can get to parts (like the valves) faster. Hmmmm...would the thicker oil really drain back slower though?