Which grade for the least consumption?

The Critic

Thread starter
Joined
Aug 30, 2004
Messages
28,221
Location
CA
Would you be able to explain using 10W-20 per Dave's suggestion? Have you decided what you will do?
The conversation will take place next week.

You got the consumption down to 8 Oz on a FB25 just by running some HPL engine cleaner??? Impressive.

Use whatever grade you used that gave you that consumption. Any FB25 with some mileage, I'd say over 50k that uses 1/2 quart over 4k miles, I'd tell that owner to pick up a lottery ticket.

Although I never tried it, I have a friend with 2 of these engines. He said he had good luck with installing restrictors on the hoses that go from the vc to the intake. That's one thing you might want to experiment with if you have time.
It was Havoline ProDS 0W20 with HPL Engine Cleaner for 2K+.

We're pretty strict on smog in CA; I think any modifications to the crankcase vent system will likely result in a failure during the visual inspection portion of the test.

CAFE awards and advertised fuel economy. Tthere is no good technical reason to do so. Film thickness is what protects and prevents wear.
I'm not too concerned about engine wear - the car will likely be sold/traded before 200k anyway. Probably 150K.
 
Joined
Oct 7, 2012
Messages
3,778
Location
Staten Island, NY
Glad to hear someone else is also having good luck with HPL EC in an oil burner 👍

Where is this mysterious 10w20, I wanna try it 😲

Personally, for ease of daily use, and reduced chances of running the engine dry (many Subarus have unlived this way) I'd just run the 0w40

I just bought 2 bottles of M1 0w40 to try in my oil burning project 2AZ
 

Shel_B

Site Donor 2022
Joined
Aug 7, 2020
Messages
2,819
Glad to hear someone else is also having good luck with HPL EC in an oil burner 👍

Where is this mysterious 10w20, I wanna try it 😲
 
Joined
Jan 4, 2016
Messages
2,539
Location
704
Works for me.
It works for millions of people. For the duration of the warranty period. Shortly after warranty millions of those people deal with oil consumption issues though. Those who upped the oil grade early enough, usually end up avoiding oil consumption issues until much higher mileages.
Of course engines that have factory defects end up with oil consumption regardless, but those aren't the engines I'm talking about here. My message is more about normal wear on cylinder walls and piston rings, as well as oils resistance to carbon build up in the ring lands.
Viscosity is only part of the puzzle though, good additives have huge impact as well.
 
Joined
Dec 29, 2010
Messages
5,874
Location
Paramount, California
Continuation of this: https://bobistheoilguy.com/forums/t...mption-updated-at-post-64.336079/post-6219232

FB25 Forester. After running 1 qt of @High Performance Lubricants Engine Cleaner 30 for 2000 miles, the oil consumption is significantly reduced: only 1/4-1/3qt of oil was lost during this timeframe. Normally this engine drinks a full quart of 0W20 every 2500-3000 miles.

I’ll assume the HPL Engine Cleaner helped unstick the rings (to an extent) and I would like this process to continue.

I have 3 of their oils in my inventory:

Standard PCMO 5W20
Standard PCMO 10W20
Standard PCMO 5W30

Which one is likely to result in the least oil consumption? Note: this vehicle may see some cold temperatures during winter months, but it will not be below 0F.
I don't know. Does thicker oil help? It helps a lot with worn valve-stem oil seals, but I don't know about loose rings. Give Mobil Delvac Extreme 15W-40 a try and let us know.
 
Joined
Aug 25, 2018
Messages
2,968
Location
South Carolina
Another vote for 10W-20. I'm running it in my Mustang currently.

What Lake said in that video is absolutely correct. The hone is very important to the rings used and the oil viscosity. It all has to match. Newer engines are using thinner and lower tension oil rings, with reduced finish roughness, and that favors a lower viscosity oil. CAFE is a big influence in them moving that direction, but the increase in EV sales is big motivator as well. Improvements in combustion efficiency, friction reduction, and ring seal all equate to better fuel efficiency.
 
Joined
Dec 29, 2010
Messages
5,874
Location
Paramount, California
Another vote for 10W-20. I'm running it in my Mustang currently.

What Lake said in that video is absolutely correct. The hone is very important to the rings used and the oil viscosity. It all has to match. Newer engines are using thinner and lower tension oil rings, with reduced finish roughness, and that favors a lower viscosity oil. CAFE is a big influence in them moving that direction, but the increase in EV sales is big motivator as well. Improvements in combustion efficiency, friction reduction, and ring seal all equate to better fuel efficiency.
I don't know about that. Part of the cylinders/rings run in the boundary-lubrication regime; therefore, a thicker base oil (not just a thicker finished oil) is your best friend. A 10W-20 is a good start, albeit difficult to find, but you can move to a 15W-40 in warmer climates.

Also, he is already seeing high consumption with thinner oil, and you can't expect things to change if you simply use another thin oil. I don't know if a 15W-40 would reduce future problems or make them worse, but you can give it a try. You can even try a 20W-50.
 
Joined
Aug 25, 2018
Messages
2,968
Location
South Carolina
I don't know about that. Part of the cylinders/rings run in the boundary-lubrication regime; therefore, a thicker base oil (not just a thicker finished oil) is your best friend. A 10W-20 is a good start, albeit difficult to find, but you can move to a 15W-40 in warmer climates.

Also, he is already seeing high consumption with thinner oil, and you can't expect things to change if you simply use another thin oil. I don't know if a 15W-40 would reduce future problems or make them worse, but you can give it a try. You can even try a 20W-50.

The rings see boundary lubrication at TDC and BDC transitioning to/from EHD and HD at ~20° each way from BDC and TDC. Any influence from a thicker film would only be seen in those areas. I think the most it would do is help the rings make that transition into EHD a little bit sooner. Maybe 18° from TDC/BDC instead of 20°. If the oil film is too thick, ring seal can be compromised. Now, how much so in a commuter car running at 2000-2500 rpm, probably not much. It shows up in high rpm racing engines for sure. That said, that commuter car is likely running 10-15" intake vacuum while cruising which could certainly aid in pulling oil past compromised rings.
 
Joined
Dec 29, 2010
Messages
5,874
Location
Paramount, California
The rings see boundary lubrication at TDC and BDC transitioning to/from EHD and HD at ~20° each way from BDC and TDC. Any influence from a thicker film would only be seen in those areas. I think the most it would do is help the rings make that transition into EHD a little bit sooner. Maybe 18° from TDC/BDC instead of 20°. If the oil film is too thick, ring seal can be compromised. Now, how much so in a commuter car running at 2000-2500 rpm, probably not much. It shows up in high rpm racing engines for sure. That said, that commuter car is likely running 10-15" intake vacuum while cruising which could certainly aid in pulling oil past compromised rings.
Cavitation? I doubt it would be a problem in a Subaru.

 
Joined
Dec 29, 2010
Messages
5,874
Location
Paramount, California
Not sure if they are loose. I think the rings are/were stuck or clogged since using the Engine Cleaner has improved the consumption.
Isn't it a low-mileage vehicle? If dirty rings are happening so fast, the neighbor may want to opt for M1 FS 0W-40, which contains POE, or any other oil that contains POE.
 

Shel_B

Site Donor 2022
Joined
Aug 7, 2020
Messages
2,819
Isn't it a low-mileage vehicle? If dirty rings are happening so fast, the neighbor may want to opt for M1 FS 0W-40, which contains POE, or any other oil that contains POE.
Isn't that the basis for HPL EC and HPL's regular oils?
 

The Critic

Thread starter
Joined
Aug 30, 2004
Messages
28,221
Location
CA
Isn't it a low-mileage vehicle? If dirty rings are happening so fast, the neighbor may want to opt for M1 FS 0W-40, which contains POE, or any other oil that contains POE.
It has just over 100k now, but has exhibited oil consumption for at least 30K miles.
 
Top