Changing Viscosity for Summer and for Cleaning?

[Slick]

Hello all, I have a 2015 F150 5.0 (Gen 2 coyote v8 engine) that I purchased not long ago. Very very long story short...I eventually found out that the engine was sludged. Extremely sludged. So I decided to dismantle the engine and clean it by hand, replace any parts needed, and reassemble it. I'm just a couple weeks away from having it reassembled and running again. Over 90% of the sludge is gone, and there are only a few really small places/corner that have a little sludge residue left. Ford originally called for 5W-20 in this engine...but then due to common oil pressure/viscosity related issues with VCT solenoids & cam phasers, ford later officially supported anything between 5W-20 and 5W-50. Many ford 5.0 owners that have switched away from 5W-20 to higher viscosities such as 5W-50 say that their truck has never ran better...and especially in hot weather climates.

I originally planning on refilling the newly rebuilt engine with Valvoline Restore & Protect 5W-30 in order to help continue the internal cleaning process. However after more research I'd really like to run 5W-50 in the engine due to the way the higher viscosity affects the timing components, and due to its additional protective nature in hot weather...as I live in south Texas where its regularly 95-100 degrees with 85% humidity for many months (tropical environment)...and mild winters that sit between 30-70 degrees and only last for a few months.

Here's my thought/question: Would it be ok to use a Amsoil 5w-50 during the summer months (to protect engine wear with the hot weather, to help timing components operate better)...then switch to Valvoline R&P 5w-30 during the winter months (to help continue cleaning)? Would changing brands & viscosities cause any problems?

I wish Valvoline made a R&P in 5W-50...but they don't.

Thanks!

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Wristcheck

Great job cleaning the massive amount of sludge buildup. Do you know what area and how the truck was used before you purchased it?

My exposure to extreme sludge build up causes are as follows:

- Poor PCV system designs
- Short trips in cold weather
-Coolant leaks into crankcase
-Neglected oil changes and low quality oil

My Great Uncle had a 1985 Oldsmobile 88 (last of the RWD) with a carburetor fed pushrod 305 V8. Low mileage 5 year old car under 8,000 miles at the time I visited him. He retired in Clearwater FL and did not drive much with trips shorter than 5 miles round trip. The key sludge builder, I suspect, was he would start up and idle the engine 2 to 3 minutes ever day thinking he was doing good. (as expected he often had to hook up a battery charger to keep the battery charged). My Mother inherited the car years later and we pulled the RA cover to see extreme sludge buildup. We then took the oil pan, the other RA cover, timing chain cover and cleaned as best we could; changed the PCV valve and started frequent oil changes. No engine issues later.

 

[Wristcheck]

I would probably run any 0W-40 or 5W-40 year round. Mobil 1 FS 0W-40 is very budget friendly and widely available at any Walmart and auto parts store.
No need to change the oil in the winter, even 5W-50 will be fine, you don't get much cold. 5W oils are fine until -30°C (-22°F).

Agreed. I would love to run W-40 or W-50 year round...however I feel that I really need the Valvoline Restore and Protect's cleaning capabilities...for both the remaining pockets of sludge...and piston rings. This is why I'm debating/questioning whether I should alternate both.

 

[Wristcheck]

A short OCI is your best friend. If I were in your shoes, I would use a good 0W30 synthetic like RnP, Amsoil, HPL, or my new favorite when the price is right: Mobil 1 Cleaning Edition or whatever it is called. The engine has no idea whether it is winter or summer. I wish you the best and hope that horrendous sludge problem did not cause more hidden damage.

Thanks for your kindness!

 

[Wristcheck]

Is this you?

https://www.f150forum.com/f118/advice-needed-engine-salvageable-578896/

As a direct answer I’d be pretty unconcerned about summer viscosity given that level of sludge and deposits.

Haha...yes unfortunately that was me. What do you mean by "unconcerned" given the level of sludge? The sludge is now gone. Sorry I'm just not understanding what you're trying to convey. Thanks!

 

[Wristcheck]

I've considered similar (but adapted for the cold winters here) - Valvoline Restore & Protect 5W-30 for the summer, and Mobil 1 ESP 0W-30 for the winter.

That makes total sense as you're more concerned with oil flow in the cold season. I would prob do the same if I were you. However, I'm more concerned about wear protection, oil pressure, and viscosity in the really hot summer months. I'm not concerned at all about the 5W part...just the -30, -40, or -50 for both the heat/engine itself.

 

[Canyonero]

This kind of sludging can happen with a defective thermostat that is stuck open, preventing the engine and oil from reaching a high enough temp to burn off moisture in the crankcase.

I had a '92 Cherokee that had similar levels of sludge buildup caused by a stuck thermostat. Living in an extremely humid environment makes this a lot more severe than in dry places.

If you haven't checked the thermostat, you probably should.

I'd just stick with 5W-30 R&P all year like some others have said.

 

[scrllock]

No, I don’t know how long the previous owner went without an oil change. How is your truck reacting to the 5W-30? And what climate are you in?

That could be its first then. I assumed it was at 200k+ with infrequent semi-synth changes.

It's very good. Couple mechanic friends saw it and commented on the lack of any typical coyote noises. Surprising since usually Mobil is a little noisy compared to Castrol/SOPUS for me. The fuel efficiency difference is going to be minimal, and if anything, my fuel economy is better than the prior owner's average. I attribute that mostly to maintenance (clean filters, new spark plugs, plenty of pressure in the tires) versus anything related to oil tho.

I'm in Michigan but on a water-cooled engine this is a minimal difference. These engines are extremely solid even with average care, you unfortunately got one of the worst I've seen.

Frankly almost any full synthetic of 20 grade and above will be absolutely fine in this engine if you just.. change it. These engines are extremely robust and very easy on oil. I would really consider saving your money on a boutique like AMSoil. If you want to drop the money on that, put it in the drivetrain fluids.

Agreed. I would love to run W-40 or W-50 year round...however I feel that I really need the Valvoline Restore and Protect's cleaning capabilities...for both the remaining pockets of sludge...and piston rings. This is why I'm debating/questioning whether I should alternate both.

If you didn't tear down the bottom end, it might be worth running a rotation of VRP, HPL EC, or similar. If you want to actually monitor progress, run compression tests after each oil change. That said, I do think if you've gone to the effort of fully tearing the motor apart, it's worth hot dipping it so you don't have to deal with trying to clean it with oil. If I were given those requirements, I would just run M1 0w40 FS, maybe with some HPL EC at first to get rid of the last bits you missed. VRP would be totally fine as well though. Keep in mind there are millions of these out there running 5w20/5w30 towing around the country for 200k+ miles.

 

[kschachn]

Haha...yes unfortunately that was me. What do you mean by "unconcerned" given the level of sludge? The sludge is now gone. Sorry I'm just not understanding what you're trying to convey. Thanks!

Because if you want to clean up something it’s not the grade that makes a difference. It’s the oil chemistry. Oil grade neither contributed to nor assists in removing such deposits.

 

[Wristcheck]

Wristcheck

Great job cleaning the massive amount of sludge buildup. Do you know what area and how the truck was used before you purchased it?

My exposure to extreme sludge build up causes are as follows:

- Poor PCV system designs
- Short trips in cold weather
-Coolant leaks into crankcase
-Neglected oil changes and low quality oil

My Great Uncle had a 1985 Oldsmobile 88 (last of the RWD) with a carburetor fed pushrod 305 V8. Low mileage 5 year old car under 8,000 miles at the time I visited him. He retired in Clearwater FL and did not drive much with trips shorter than 5 miles round trip. The key sludge builder, I suspect, was he would start up and idle the engine 2 to 3 minutes ever day thinking he was doing good. (as expected he often had to hook up a battery charger to keep the battery charged). My Mother inherited the car years later and we pulled the RA cover to see extreme sludge buildup. We then took the oil pan, the other RA cover, timing chain cover and cleaned as best we could; changed the PCV valve and started frequent oil changes. No engine issues later.

Thanks for reaching out. I have looked into this quite a bit and have come to the same/similar assessment you have experienced. Also, I should note that it's one thing for people to see a pic or video of sludge on the internet and claim "lack of oil changes"...but seeing the sludge in person and tearing down the engine and seeing the evidence of how different areas were affecting + knowing the backstory of past ownership habits and maintenance...starts to paint a story that maybe isn't just about a lack of oil changes only. You and I have the unique connection of both seeing the sludge face to face, seeing how it affected different areas of the engine, knowing the vehicle's history, and both dealt with cleaning it out...and with all that evidence we have the same/similar assessment of causation. I doubt that's a coincidence. I might be wrong, but in my studies & hands on experience, I think there's more to it than just "they didn't change the oil"...and I think you hit the nail on the head.

My studies & personal journey have me thinking it has something to do with...
1. Shear/breakdown of oil (either due to not changing oil and, crappy quality oil, or another element causing it to break down)
2. + Short trips (broken down oil starts to coagulate and never gets opportunity to heat up and flow properly)
3. + poor PCV design (exhaust gasses somehow play a role in oil breaking down or coagulating?)
4. + Could humidity (with the short trips) play a role...moisture in crankcase?

I do believe the PCV system has something to do with it because when removing the valve covers my passenger side (PCV side) sludge was twice as bad as my drivers side.

I also did extensive research on this truck's history, and it was apparently owned by an elderly man who hardly drove it avg 5-6K miles a year. I bought it in 2025...and from 2015-2025 he drove it only 60k miles. He would use it to make short trips to the store and back. Otherwise, It mainly sat in his driveway. It's my understanding that he changed the oil maybe 3-4x during ownership...so let's call it every 15-20K miles. And once again, this is Texas gulf coast hot and humid weather..much like Florida. Sounds like a very similar situation to your father's car.

I'm glad you were able to clean it and keep it running. That's encouraging, because most people have told me my engine is gone...do not resuscitate. But I have hope because I don't see evidence of damage...just normal wear. I as well have changed all PCV components, sensors, etc. I'm now just trying to decide what oil to refill it with. Thanks for your story, it helps a lot!

 

[Sequoiasoon]

That might have been a great test bed for BG Dynamic with some before and after pictures.

 

[tcp71]

Our 2015 coyote gets mobil or edge 0w40 and runs like a top.

 

[Wristcheck]

This kind of sludging can happen with a defective thermostat that is stuck open, preventing the engine and oil from reaching a high enough temp to burn off moisture in the crankcase.

I had a '92 Cherokee that had similar levels of sludge buildup caused by a stuck thermostat. Living in an extremely humid environment makes this a lot more severe than in dry places.

If you haven't checked the thermostat, you probably should.

I'd just stick with 5W-30 R&P all year like some others have said.

Very good point! Will do thanks!

 

[Wristcheck]

Our 2015 coyote gets mobil or edge 0w40 and runs like a top.

Yep I believe it! I know that -40 or -50 would be best...but it still needs some internal cleaning done, and the test results/ cleaning evidence that I've seen on Restore and Protect is impressive, and would probably be perfect for addressing the last few areas. Maybe I run R&P for a year or so with 3K change intervals...and then switch to -40 or -50?

 

[Wristcheck]

That might have been a great test bed for BG Dynamic with some before and after pictures.

I personally have not seen evidence of what BG and others alike claim. Throughout my journey, I've become skeptical of these engine oil cleaning additives such as BG and others. I know they're all popular, and many people told me do try them, and I did look into them heavily...but I just don't see reliable evidence of their effectiveness. If anything, I think my situation would have hurt them and their claims. Also, I should note...this is caked on sludge (not a thin layer of grime). The only way to remove it, is to physically remove it. BG and others would just flow right over it. Even if it did work...it would take 1,000 flushes to produce significant results...haha.

 

[K2K2]

Dude - as clean as you're making it with your disassembly plan (nice job BTW!), there's absolutely no need for VRP, especially if you're going to run Amsoil......it's already clean! Those small corner areas won't cause an issue and will clean up with time.

In your place, I'd just run the 5w50 year 'round.

 

[4wd]

Geez - a run on a quality synthetic would be a good first pass.

 

[Sequoiasoon]

I personally have not seen evidence of what BG and others alike claim. Throughout my journey, I've become skeptical of these engine oil cleaning additives such as BG and others. I know they're all popular, and many people told me do try them, and I did look into them heavily...but I just don't see reliable evidence of their effectiveness. If anything, I think my situation would have hurt them and their claims. Also, I should note...this is caked on sludge (not a thin layer of grime). The only way to remove it, is to physically remove it. BG and others would just flow right over it. Even if it did work...it would take 1,000 flushes to produce significant results...haha.

I saw some videos from "watch JR Go" on YouTube with his Dodge Dart, some other maybe Sherwood Auto and some independent others.

I do like some BG Products, others not as much. Many of the videos I saw with the BG Dynamic, they seemed to be impressed with how it worked.

Either way you already did all the work to get it really good so at a lower cost and availability Restore and Protect, Mobil 1 ESP 0W-30 would be good choices. High Performance Lubricants a bit more $$ but ship to you. I don't know where Amsoil falls on the cleaning vs working well to stay clean if used from early.

Sadly MANY members here have been disappointed with what we all thought were high quality full synthetics, not run extended use and still developed oil burning issues. Some that were resolved or greatly reduced by the above.

 

[Japanese]

Extremely sludged. So I decided to dismantle the engine and clean it by hand, replace any parts needed, and reassemble it.

What do you mean by dismantle? Did you open the oil pan? Did you take the pistons out?

Agreed. I would love to run W-40 or W-50 year round...however I feel that I really need the Valvoline Restore and Protect's cleaning capabilities...for both the remaining pockets of sludge...and piston rings. This is why I'm debating/questioning whether I should alternate both.

If your engine is spec'd for 5W-20 and your main concern in to continue the internal cleaning—you have 2 options:

1. Run VRP 5W-30 year round from now on for unspecified time. Most likely at least 3-4 oil changes.

2. Use the oil you like and also get one of the HPL engine cleaners and use them together for certain time, but for sure more than once.

HPL have 2 cleaning oils SAE 30 and SAE 40 that can be mixed with any oil:
https://www.advlubrication.com/collections/automotive-lubricants/products/engine-cleaner

The difference would be that the VRP is proven to clean not only sludge and varnish, but also to clean piston rings too. And the other engine cleaners are not specialized in cleaning specifically piston rings. But they may clean quicker the other engine internals.

If you had that much sludge in your engine I would inspect the oil filter every 1,000 miles (regardless of the cleaning oil I use), if it's cartridge filter and possible change it, if it has a lot sledge in it. If it's a regular metal filter, I would change it after 1,000-2,000 miles and cut it open to inspect any collected material and decide when to change the next filter.