Thick vs Thin - Castrol Edge 5W-20 @ 8693 miles & Castrol Edge EP 5W-30 @ 8200 miles in a 2019 Mustang GT

[RevvCats]

A lot of data here. Not a perfect comparison Regular Edge 5w20 vs Edge EP 5w30 and that EP saw a chunk of winter driving but here’s how the two looked in my Mustang over semi-long intervals.

Executive summary

Edge EP 5w30 @ 8200 miles
Time: March 2024 - February 2025
Fe+Al+Cu = 10 / 8.2 ~ 1.2 ppm/1k
Oxidation: 12
Boron: 37 ppm
KV100: 10.2 cSt

Edge 5W20 @ 8693 miles
Time: March 2023 - October 2023
Fe+Al+Cu = 17 - 6 @ 228 miles / 8.465 ~ 1.3 ppm/1k
Oxidation: 15, 8 VOA
Boron: 33 ppm, 151 ppm VOA
KV100: 8.5 cSt, 8.3 cSt VOA

The 5w20 run started with Blackstone but I switched to Oil Analyzers after getting hip to measuring oxidation and I also had some 5w-20 left over in the bottle to send in for a VOA. I was going to try SpeedDiagonstix the kits through Amsoil are half the price. I’d say that oil came back looking pretty good at the end, boron took a big hit but hey that just means it’s doing its job suspending crud that gets trapped in the filter. The Oil Analyzers report has the viscosity flagged but that’s because the viscosity wasn’t correctly updated and they were thinking it was still the 5w-50 I was using at the track.

Edge EP 5w-30 also looks pretty good, this was put in after the track and that used oil was really clean of wear metals (aside from a little lead contamination) so I didn’t think it was too important to do a 200 mile baseline measurement. I also didn’t have any unused oil to send in for a VOA and Castrol updated all the bottles so I don’t know if the Edge EP you buy today is the same as the old stuff.

One thing that struck me, from an additive standpoint the Edge EP doesn’t seem different from the regular Edge. Similar titanium, moly, zinc, and phosphorus levels. Whats the difference between the two? Better viscosity improvers? Different base oils?

I’ll give the win to team thick because
the 5w-30 saw three months of winter use and from past oil analysis I’ve seen wear really tick up when it gets cold, but it’s not like 5w-20 was out there wrecking up my engine.

I’ve been saving the used oil filters so when the weather gets nicer and this inch of perpetual ground ice thaws I’ll cut them open and see if there any noticeable difference.

 

[Patman]

A difference in viscosity of just 2cst at 100C isn’t exactly “thick vs thin” here

 

[wareze]

Nice to see some Castrol for a change. Held up nice

 

[fantastic]

Both oils seem to do good for you but nice to have a slight buffer for fuel dilution. Look forward to seeing your oil filter cuts.

 

[chainblu]

Thin vs thinner

 

[RevvCats]

A difference in viscosity of just 2cst at 100C isn’t exactly “thick vs thin” here

There’s an active thread right now debating why people use 20 weight oils instead of 30, the thins on one side and the thickies on the other. Yeah it is only a few cSt difference, that’s true for many 5w-20 and 5w-30 oils, but so many people are convinced 20 weight oils are some sort of government or manufacturer conspiracy to destroy our engines.

 

[Patman]

There’s an active thread right now debating why people use 20 weight oils instead of 30, the thins on one side and the thickies on the other. Yeah it is only a few cSt difference, that’s true for many 5w-20 and 5w-30 oils, but so many people are convinced 20 weight oils are some sort of government or manufacturer conspiracy to destroy our engines.

And it’s always funny to read those threads, people arguing over such a minor viscosity difference between the two.
But a more realistic “thin vs thick” comparison would be going from a 0w20 to a 0w40.

 

[RevvCats]

Nice to see some Castrol for a change. Held up nice

If NAPA puts 5w-50 Edge on sale again this year I’ll buy boxes of that stuff.

 

[scoot]

If NAPA puts 5w-50 Edge on sale again this year I’ll buy boxes of that stuff.

I will also it's good for my model T

 

[TiGeo]

I see no meaningful difference in the UOA data plus you can't use it that way anyway.

 

[RevvCats]

I see no meaningful difference in the UOA data plus you can't use it that way anyway.

Referring to my comment about the EP vs non EP additive pack or just comparing the amount of wear metals between the two oils?

 

[JavierH19]

The pds of the older castrol EP 20k used to say 0/5w-20 both had a 2.6 hths and 2.9 for the 5w-30 and that likely hasn't changed. At 2.9 hths that 30 grade is 20 to me so they're the same thin oil as far as i can tell.

 

[TiGeo]

Referring to my comment about the EP vs non EP additive pack or just comparing the amount of wear metals between the two oils?

Comparing anything using UOA beyond viscosity numbers.

 

[2.7ecoboostFordBronco]

Interesting test, thanks for sharing. Looks like the wear metals were ~50% lower with the 30? Inconsequential and within the margin of error for the analyses? Maybe, but still entertaining to read about. Now do a dyno with each one to see if you gain a horsepower with the 5W-20

 

[kschachn]

Interesting test, thanks for sharing. Looks like the wear metals were ~50% lower with the 30? Inconsequential and within the margin of error for the analyses? Maybe, but still entertaining to read about. Now do a dyno with each one to see if you gain a horsepower with the 5W-20

And with all the uncontrolled variables in everyday driving you don't know if that was due to the oil or something else.

Comparative wear analysis between oils isn't accomplished with a simple UOA.

 

[kschachn]

There’s an active thread right now debating why people use 20 weight oils instead of 30, the thins on one side and the thickies on the other. Yeah it is only a few cSt difference, that’s true for many 5w-20 and 5w-30 oils, but so many people are convinced 20 weight oils are some sort of government or manufacturer conspiracy to destroy our engines.

They are for improving fuel economy and nothing else. If that is your sole and primary objective then they are beneficial. But not for anything else.

 

[RevvCats]

Interesting test, thanks for sharing. Looks like the wear metals were ~50% lower with the 30? Inconsequential and within the margin of error for the analyses? Maybe, but still entertaining to read about. Now do a dyno with each one to see if you gain a horsepower with the 5W-20

I actually know a shop that has their dyno elevated so you could lift the car up, strap down, and fairly easily change the oil between sets of pulls. Look at different grade oils with thicker kv100 viscosities or get a set of oils with similar kv100 values but different HTHS viscosities.

It’d be fun, but a few hours on the dyno and 10 quarts for each oil would add up quick.

 

[Patman]

I actually know a shop that has their dyno elevated so you could lift the car up, strap down, and fairly easily change the oil between sets of pulls. Look at different grade oils with thicker kv100 viscosities or get a set of oils with similar kv100 values but different HTHS viscosities.

It’d be fun, but a few hours on the dyno and 10 quarts for each oil would add up quick.

The problem with that is you won’t see much more than maybe a 1 or 2 horsepower difference between different oils, but yet if you do a bunch of dyno pulls you will see the horsepower vary by 5-10 just from one pull to the next without any changes at all. So you really wouldn’t be able to discern a difference between different oils.

 

[dnewton3]

Additive wear metal counts reduced to a singular wear rates.
Unequal environmental conditions.
Switching lab services.
Running only 1 or 2 samples of each and then declares "I’ll give the win to team thick ..."


Garbage garage science at its best.
SMH (sigh ......)