Any downsides to thicker oil?

[aquariuscsm]

Originally Posted By: CATERHAM
I believe the old oil axiom applies;
"the oil should be as thin as possible and just as thick as necessary".


^^Probably the best oil advice ever. You don`t want too thin,and you don`t want too thick,but a happy medium.

 

[StevieC]

I beat the snot out of the Santa Fe tonight on the back country roads because it was overdue for an Italian Tune-Up of sorts and I like to Red-Line it once and a while. (Warmed up of-course)

It definitely felt much smoother and seemed to red-line faster I know it's probably in my head but I could swear it does.

The engine seems quieter about it too...

5w20 RLI with a Hyundai filter at the moment and 328K KM's on the clock.

 

[Shannow]

Originally Posted By: CATERHAM
The biggest downside is the myth that you're providing more lubrication protection with a thicker oil.


A thicker oil will always have a thicker oil film under all operating conditions, and thus greater parts seperation between the bearing and journals.

Whether you need it or not is another matter

Originally Posted By: CATERHAM
I believe the old oil axiom applies;
"the oil should be as thin as possible and just as thick as necessary".


That's a beauty

 

[spasm3]

i could probably fill my escape with all mmo (5w) and it would most likely run great and "feel like its running better" but how long would it last? not too long. i'm leary of the it feels like it runs smoother comments. the proof is in the longevity and the gas mileage. I see no difference in my escape's gas mileage from the 5w 20 it came with or the 5w 40 i'm running now.

 

[StevieC]

Like I posted above (I think) my dad's Windstar that he recently got has run 5w20 it's whole life and it's running great with over 300K KM's on the clock. Doesn't burn or leak oil and passes the emissions test with flying colours.

I would say that speaks for longevity no?

 

[spasm3]

Originally Posted By: StevieC
Like I posted above (I think) my dad's Windstar that he recently got has run 5w20 it's whole life and it's running great with over 300K KM's on the clock. Doesn't burn or leak oil and passes the emissions test with flying colours.

I would say that speaks for longevity no?


and that looks like it works great for that vehicle / drivers use, it however does not fit mine. Again its what you drive and how you drive it.

 

[StevieC]

This guy (our neighbour) towed a boat with the van all summer, always had it full of junk going to the dump, and then had his family in it all the time going somewhere.

It saw regular oil changes but not at the interval I would reccomend for the stress.

He also floored it cold all the time from the driveway because our road is 80KPH

I dunno, I think that is pretty heavy stress situation?

 

[demarpaint]

Originally Posted By: StevieC
Like I posted above (I think) my dad's Windstar that he recently got has run 5w20 it's whole life and it's running great with over 300K KM's on the clock. Doesn't burn or leak oil and passes the emissions test with flying colours.

I would say that speaks for longevity no?


+1 on the longevity! 5W20 is fine for applications that call for it. Old habits die hard for many of us, oil is evolving, the 20 grade oils seem to be doing their job, and quite well.

 

[spasm3]

seems to work for him so great! It also does not mean that everybody needs the thin oils. If it works for you fine. My escape has not seen any 20w oil since 2001 and it won't!!

 

[StevieC]

No just wanted to tell you the history of the vehicle... It does have some piston knocking when cold but only on one cylinder and that could be either a defect, because of the lack of maintenance or just old age.

I on the other hand have always run 30wt oil in my 5w20 spec'ed Santa Fe until recently because I didn't believe in 20wt oil. It was only recently and a few experimental times that I ran the 5w20 and it does seem noticeably better.

I most likely will continue using the 30wt because it is generally easier to find in a synthetic and is a tad cheaper than the 20wt's and does the job for me just fine.

 

[StevieC]

Maybe I should be running a 40 or 50 weight in the summer and a 30 or 20 in the winter?

 

[tig1]

Originally Posted By: StevieC
Maybe I should be running a 40 or 50 weight in the summer and a 30 or 20 in the winter?


StevieC,
We used to do that in the 60s and early 70s. I used Valvoline straight 20wt in the winter, and 30wt in the summer. But with oils today that is no longer needed. I would use what your engine requires and keep maintaining it well, as you are already doing. By the way , aren't you picking up some PP or PU right away? That will work well in your engine.

 

[StevieC]

Yeah... Dad was tired yesterday and I was busy today so we might go to Buffalo on the weekend.

 

[CATERHAM]

I beat the snot out of the Santa Fe tonight on the back country roads because it was overdue for an Italian Tune-Up of sorts and I like to Red-Line it once and a while. (Warmed up of-course)

It definitely felt much smoother and seemed to red-line faster I know it's probably in my head but I could swear it does.

The engine seems quieter about it too...

Steve, don't forget, the HTHS vis of the bio-ester RLI 5W-20 you're running is likely around 3.0 cP and therefore the operational viscosity more on par with a light dino or GP III 30wt.

When you switch to PU 5W-20 with it's HTHS vis of 2.7 cP, the actual operational viscosity should be noticeably lower. Since you have an oil pressure gauge in your truck I'd be interested to know how much your hot oil pressure drops at elevated rev's vrs the RLI; comparing at the same exact rpm.

 

[tradosaurus]

Well I do live in a warmer climate (Texas) but I've put 15W/40 Diesel oil in Honda and Mazda car and the mpg was never affected. I also put it in a 4 cylinder Ranger and 8 cylinder E350 van with no MPG decrease.

I ran that grade of oil through summer and "winter".

 

[Gary Allan]

Originally Posted By: tradosaurus
Well I do live in a warmer climate (Texas) but I've put 15W/40 Diesel oil in Honda and Mazda car and the mpg was never affected. I also put it in a 4 cylinder Ranger and 8 cylinder E350 van with no MPG decrease.

I ran that grade of oil through summer and "winter".


What was the typical trip length for these vehicle and what was your alternative fill? On another post, you've stated that you've used the 15w-40 for (was it) 3 or 4 years. That sorta implies that you've done little in the form of comparison on that unit.

If you're doing longer mileage over one warm up cycle, the difference between a xW-20 and 20w-50 will be in the fractional percentile and could swing either way. Try that with 4 mile events on an ongoing basis and I assure you that you'll see a difference and it can be substantial. That's the whole idea with lighter weight oils. You're reducing the parasitic losses experienced during the warm up phase of the engine. That's about a 20 minute period.

Oils look more alike as they warm.

 

[Jim Allen]

Originally Posted By: CATERHAM
I believe the old oil axiom applies;
"the oil should be as thin as possible and just as thick as necessary".


Never heard that applied to oil, but the old Land Rover/Camel Trophy off-highway driving creedo that was pounded into us was:

"As slowly as possible, as fast as necessary."

I'm adapting the oil one to

"As thin as possible, as thick as necessary."

And I will use it shamelessly!

 

[Jim Allen]

Originally Posted By: CATERHAM

When you switch to PU 5W-20 with it's HTHS vis of 2.7 cP, the actual operational viscosity should be noticeably lower. Since you have an oil pressure gauge in your truck I'd be interested to know how much your hot oil pressure drops at elevated rev's vrs the RLI; comparing at the same exact rpm.


That's an interesting ponderment. Will the oil pressure change noticeably with an increase in HTHS when the base 100C viscosity stays the same, or similar?

 

[il_signore97]

Originally Posted By: Jim Allen
Originally Posted By: CATERHAM

When you switch to PU 5W-20 with it's HTHS vis of 2.7 cP, the actual operational viscosity should be noticeably lower. Since you have an oil pressure gauge in your truck I'd be interested to know how much your hot oil pressure drops at elevated rev's vrs the RLI; comparing at the same exact rpm.


That's an interesting ponderment. Will the oil pressure change noticeably with an increase in HTHS when the base 100C viscosity stays the same, or similar?



If the oil pump is in bypass (which it most likely will be at or near redline), then no, there will be no noticeable difference in oil pressure as measured by the gauge. However, the engine will see a difference in flow between the two oils, but that difference cannot be measured easily.

 

[StevieC]

Caterham:

Yeah Terry told me that there isn't much difference from the 30wt and the 20wt in the RLI and that the 5w20 RLI is a solid 20wt verging on a 30wt so maybe that is why it is the sweet spot for this engine.

Maybe any thin 30 will do nicely and maybe it is what I will stick with.

Maybe when I pick-up some Ultra I will get a 20 & 30 and see which seems to be better and if neither I might go back to RLI 5w20 because the engine truly is running sweet as far as my butt and ears can tell!