how come so many people change to a thicker oil or think there oil is too thin?

Messages
53
Sorry to bring this up if its already been spoken about. So what I have read is that a 5w20 is usually just oem fill for most vehicles because apparently they can save about 1% of fuel economy compared to a 5w30 oil and that big difference across there entire fleet results in meeting the requirements of CAFE/EPA or whatever. However tons of people seem to think that a 5w20 is too thin and that a 5w30 would provide better protection and that most engines need thicker oil. I am a man of following owners manuals and what engineers and manufacturers say, and if a vehicle says 5w20 then I use that and if a diff vehicle says 5w30 then i use that. I assume the vehicles that have 5w20 have tighter tolerances compared to a vehicle that is prescribed to take 5W30.


So what I wanted to ask is that is there actual proof or evidence or is it just hearsay that 5w20 is "too thin" and that a 5w30 would provide more protection and that any vehicle that has 5w20 would prefer a "thicker oil"?

In my uneducated opinion which could be totally wrong is that people tend to overthink stuff too much and that we shouldn't be changing our oil weights from what the manufacturer says unless for example we live in a climate very very cold or very very hot because i assume the manufactuer assumes normal temperature conditions. I feel like a 5w20 probably provides enough protection and I don't think a manufacturer or engineering team would prescribe our vehicles with a thinner oil if they would not be protected by that certain oil weight etc. Unless there is proven evidence from maybe labs or UOA's or something else to prove it, I don't think my opinion would change. For example if a UOA shows that the vehicle has more wear metals with a 5w20 compared to a 5w30 then that makes sense to me and I would believe that a 5w30 protects better or whatever other test to provide evidence


even with older vehicles for examples, like do tolerances change that much in an engine in which they need a thicker oil for more protection? i dont seem to be convinced considering i know tons of vehicles that are at like 250,000 miles on the original engine using the original oil weight, so I still don't understand why so many people see the need to get a thicker oil after x amount of miles on the engine



thanks!
 
Messages
15,940
Location
...
I would say that 0w20 is more popular now than 5w20. Either way, another thick vs thin thread to add to the multitudes on here.

I also believe there is no widespread movement to change to heavier grades of oil.
 
Messages
1,535
Location
MN
Although there are a few exceptions out there, I view oil weight experimentation much like tweaking tire pressures or alignment angles. Within reason, personal preference is just that. Personal preference. If a OE said you could only use brand X fuel, and one day you decided to try brand Y knowing full well it was an acceptable substitute, would it be along the same line of thinking? No, it would be considered silly.

OE's have to provide a set of specifications to guarantee that what they're selling will do it's job safely, reliably, and perform within design parameters AT LEAST through the warranty period, although we all know modern vehicles are designed to go far beyond that.

For example: among the multitude of family vehicles I maintain are a 2011 CR-V and a 2018 Accent (same household). The Honda spec's 0W20, the Hyundai 5W20. As many K24's tend to do, the CR-V started burning about 1.5 quarts every 1k miles running 0W20. I told my dad to just buy 5W20 for both, full synthetic as that's what both have been getting since new. No HM, nothing fancy. Just quality oil. Did it have any negative effects on the Honda? Absolutely not, in fact quite the contrary. The oil burning is now down to about 1.5-2 quarts per 5k oil change.

The same can be said for tire pressure. Sure, the OE spec is optimal, however I've been running my tires about 5 pounds high on my Volt and about 3 pounds high on my Jeep and both times it's worked out great. The Volt handles sharper in corners, rides exactly the same, gets better electric range, and the tires have worn absolutely perfect for the last 25k miles. The Jeep is a lot less "floaty" with a few extra pounds, and doesn't lean quite so much on high speed curves.
 
Messages
6,384
Location
New Braunfels
I don't see cars having oil related issues so my conclusion is that it just doesn't matter for the vast majority of engines.
We would all be better served focusing more attention on our brake, transmission and power Steering fluids and our gear oil in our transfer cases is we have them and our Differentials. And if we have a breakable drive shaft having a good grease gun and grease. my Engines are “world engines” they run on a broad spectrum of engine oils just fine.
 

mazda3lover

Thread starter
Messages
53
There's plenty of info about it in the archives, tons in fact. Consider searching, and spending hours, if not days reading up on what has been hashed and rehashed hundreds of times over the years.

ahaha yeah I spent 20-30 mins researching on these boards but I couldn’t really find a definite answer. All I would read about is people saying “I run thicker because ...” etc etc.

but I could never find any proof or evidence
 

mazda3lover

Thread starter
Messages
53
Although there are a few exceptions out there, I view oil weight experimentation much like tweaking tire pressures or alignment angles. Within reason, personal preference is just that. Personal preference. If a OE said you could only use brand X fuel, and one day you decided to try brand Y knowing full well it was an acceptable substitute, would it be along the same line of thinking? No, it would be considered silly.

OE's have to provide a set of specifications to guarantee that what they're selling will do it's job safely, reliably, and perform within design parameters AT LEAST through the warranty period, although we all know modern vehicles are designed to go far beyond that.

For example: among the multitude of family vehicles I maintain are a 2011 CR-V and a 2018 Accent (same household). The Honda spec's 0W20, the Hyundai 5W20. As many K24's tend to do, the CR-V started burning about 1.5 quarts every 1k miles running 0W20. I told my dad to just buy 5W20 for both, full synthetic as that's what both have been getting since new. No HM, nothing fancy. Just quality oil. Did it have any negative effects on the Honda? Absolutely not, in fact quite the contrary. The oil burning is now down to about 1.5-2 quarts per 5k oil change.

The same can be said for tire pressure. Sure, the OE spec is optimal, however I've been running my tires about 5 pounds high on my Volt and about 3 pounds high on my Jeep and both times it's worked out great. The Volt handles sharper in corners, rides exactly the same, gets better electric range, and the tires have worn absolutely perfect for the last 25k miles. The Jeep is a lot less "floaty" with a few extra pounds, and doesn't lean quite so much on high speed curves.

oh yeah that’s fair! I completely understand changing the first number of the oil cuz that’s more dependent on where we will. For example if we live in a super cold place then 0w is good. If super hot then obvs 10w is good too. However I just don’t understand tinkering with the second number like the 20 and bumping up to a 30 etc
 

mazda3lover

Thread starter
Messages
53
For my older cars I always use the thickest I can. The newer stuff I get the thinner what is recommended for it. I think in your case the 5W-20 is good at least for winter the summer 5W-30 would be fine. I’m not sure about the fuel economy as I have never had it differ with the thickness or thinness of oil.
Thanks for the input!! Yeah I think I’m going to switch to 5w20 in the summer cuz we do get plenty hot and then back to 0w when we get super cold in the winter.

For your older cars are you changing the second value as in the one after the w? Or the first?

cuz the first makes sense to me cuz that depends more on the temperature we live around as in super super cold then 0w is a good bet. Super hot then 5w and 10w is good. However I don’t understand the movement of bumping up from a w20 to a w30
 

mazda3lover

Thread starter
Messages
53
Relax - Tinkering with that one is A-Okay too.
Thanks for the input! So do you go by the belief that a w30 would provide more protection and cars need thicker oil? Or you mean that the difference is probably negligible in engine life and just to do what you feel as in if you think a thicker oil is better then run w30 if not then w20

thanks!
 
Messages
15,940
Location
...
Thanks for the input! So do you go by the belief that a w30 would provide more protection and cars need thicker oil? Or you mean that the difference is probably negligible in engine life and just to do what you feel as in if you think a thicker oil is better then run w30 if not then w20

thanks!


it’s not w30, just plain 30 as in 30 grade.

If 30 grade is better then 40 might be even better yet, or go with a 50 grade which would solve many ills. 🧐
 
Top