20W-50 vs 5W-20: Which Oil Protects Better?

Which viscosity provides the best protection - a 20W-50 or a 5W-20? Which one delivers the lowest friction? Since friction and wear are independent of each other, we need a special engine equipped with combustion analysis to separate engine friction from the horsepower created by combustion. To measure wear, we need used oil samples of both oils to measure the wear generated in the engine during start-up cycles and full power runs. To isolate just the effect of viscosity, we choose two oils that have the exact same additive package and base oil types. This way, the only variable is the viscosity.

While we had the engine on the dyno, we also tested the impact of pre-filling (or not pre-filling) the oil filter on engine wear, and that produced an unexpected result!

To get to the sections you are most interested in, here are the chapter shortcuts:
00:01:04 - Combustion Analysis vs Dyno Horsepower Readings
00:02:48 - Test Plan
00:08:07 - Oil Pressure Rise with 5W-20
00:14:53 - Dyno Testing - 5W-20 Oil
00:16:37 - Cold Pour Comparison - 5W-20 vs 20W-50
00:19:45 - Oil Pressure Rise with 20W-50
00:20:50 - Dyno Testing - 20W-50 oil
00:21:56 - OIl Level Testing
00:27:03 - Power Test Results - 5W-20 vs 20W-50
00:30:33 - Wear Test Results - Oil Analysis Reports

For a deeper dive into the science of lubrication, check out my good friend Rafe Britton's channel @LubricationExplained

To see how friction and wear are independent of each other, check out this video:

Who is the @themotoroilgeek? I'm a Society of Tribologists and Lubrication Engineers Certified Lubrication Specialist and Oil Monitoring Analyst (I've maintained both of those for over a decade). I also worked for Joe Gibbs Racing for 12 years as their lubricant specialist. During that time, we worked with Wix Filters (one of our sponsors) to test and develop filters for our race engines. We also worked with Lubrizol and Chevron-Phillips Chemical to test and develop oils for our race cars. Following that, I was the head of R&D for Driven Racing Oil. During that time, I formulated and tested over 50 products. We also worked with Cummins, Comp Cams, Oak Ridge National Labs and General Motors on various R&D products. Those efforts are recorded in peer reviewed white papers published by SAE International and ACS Sustainable Chemistry journals. Today, I am the Tribologist for @TotalSeal , and I provide used oil analysis via SPEEDiagnostix.

#oilchange #motoroil #oilfilter #engine #dynotested #syntheticoil #oilanalysis

[themotoroilgeek]

Thanks for all the comments! I wish I had time to read and respond to all of them, but I still have a day job that keeps me very busy! Fortunately, that "day job" allows me to go to a lot of cool places where we can sneak in a video sometimes, so it works out in the end as a positive.

For those with horizontally mounted or inverted filters, see if your vehicle has clear flood mode. If so, that's a great way to prime the oiling system before the higher pressures of combustion kick in.

[EnthusiastsGarage]

This channel is a must for car enthusiasts

[LeadStarDude]

I have always prefilled my oil filters. My dad and grandpa taught me to always prefill the oil filter. They both gave a simple reason for it. Don't make the motor wait for oil.

[ryanmiskin]

I bet when you made this channel, you greatly underestimated how many people are obsessed with motor oil.

[HypocriticYT]

This channel and Project Farm has saved me $$ from not buying products with trial and error 😡 Valuable information ℹ️

[somethinlike]

Mmm project farm reference, I love when the channels I watch are watching each other.

[AmaroqStarwind]

You, Banks Power, and Project Farm are like the holy trinity of actually testing things

[hightdan]

Love the shoutout to Project Farm. Great channel.

[jrs]

Excellent job from a retired engineer. Thirty years ago, I observed similar tests for a petroleum company, studying only wear. Thus, all my grandchildren's fancy little vehicles run on 20W50 oil after 50k miles. Nine of them have 95% of original compression at over 250K miles while obtaining fuel mileage similar to when they were new.. Thanks guys.

[Maverick]

I’ve been changing the oil in all my vehicles for the last 24 years. Today was the first day I’ve ever prefilled the oil filter. My engine thanks you, Lake!

[kcdesignconcepts]

I've been an engineer and auto technician for over 40 years. I have always prefilled the filter. Even if it's on a slight angle(old fords) I would try to put as much oil in as I could without it running out.
On my BMW E36 track car, that doesn't get used a lot especially in the winter, I installed an electric oil pump. When I turn the ignition on the ECU runs that pump until I get over 30 PSI of oil pressure.
No matter how long the car sits I never have a dry start.

[RevLarry]

I was an auto mechanic for many years, never prefilled an oil filter. To the best of my knowledge no one else did. I'm refilling NOW!
You taught the old dog a new trick. Thanks for your expertly done tests. You are who I look to for knowledge on these topics.

[ZillaFullBoost]

Putting all of the bro science theories to rest 1 video at a time 👌🏽

[warrenlucier]

Prefilled my oil filters for the past 55 years and intend to do so for as long as I'm alive !

[CDOES]

My OCD is always so satisfied with this channels work. Thank you

[eDXTRe]

This is the channel we have all been waiting for, real knowledge about oil and put it to the test, in stead of underbelly Real engine, real oil analysis.
Thanks for sharing,

[Cadillac-vg]

I have my parents 58 cadillac they bought in 1960. As long as I can remember dad always ran 10 40 castrol in it. In 1982 it was given to me. By 2011 the blow by coming out of the down draft tube was just no longer tolerable. I had the engine rebuilt by a shop in business for 54 years. The gentleman who did the work was 74 years old. When the car was ready, I asked him his recommendation for the oil. He said, Castrol 20 50. That's what's in it now. I said really? He said yup trust me. Run that oil in it, these 365, 390 engines love it. We're in Southern California, no issues with the winter temps. 13 years now it's running great. And NO BLOW BY!

[hightttech]

Very intuitive results. I was always a fan of 20W-50, and these ridiculously thin oils today are due to carmakers clawing for every last MPG, and a few ppm reduction in emissions, to try to satisfy stricter and stricter government regulations.

[randyjones]

As an analytical chemist, I love seeing proper experiment design and proper sampling technique. Great job! Awesome video!

[dogdooley]

Manufacturers are under extreme pressure to achieve higher fuel efficiency and this is the main reason we have such thin oils as 0w8. Thin oils do save fuel. I will continue to use 5w30 or 0w30 in winter for all of my vehicles. If you get a new car every few years then the thin oils will be fine but I keep my cars as long as possible and 5w30 seems to be the ideal for me. The engines definitely run quieter.