Best 5/10w50 oil for winter, high RPM/high oil temperatures. Lowest outside temp -10F.

[79Subaru]

My daily driver is a 79 Subaru DL with an EA71S engine swapped in. That is a 1.6l flat 4, pushrod engine, high compression (12:1-13:1ish), low tension rings, naturally aspirated, gear drive cam, long cam duration (around 305/305 advertised). Powerband is around 4000-6700 RPM, cruising RPM is around 3500-4000 usually. Does not have an oil cooler, and has large bearing clearances. Oil temp tends to run at around 102C on the highway, but can reach as high as 130C. Likes a 50 or 60wt oil. Driven 90-95% highway, long distances. In winter I tend to run M1 FS X2 5W50. Mainly because it's easy to find. Does well for cold starts but seems to start shearing or getting thin at around 3000mi. By 5000 it is no longer usable in this engine and has to be changed (hot oil pressure too low). Been thinking about trying another oil. Molygen 5W50 looks attractive but not sure if it will really perform any better than the M1. The Kohler 10W50 small engine oil is also easy to find at Tractor Supply and has good specs. Ravenol makes a 10W50, so does HPL, and there are various motorcycle 10w50s and thin 15w50s. HPL and Amsoil also have 5W50s. There is also the ZO6 Corvette 5W50, M1 Supercar. What do you guys think will perform the best, while also not being outrageously difficult to find. Here are some spec sheets:

From these data sheets, the 10W50 Kohler Pro oil looks surprisingly good, especially for how easily available it is. The NOACK is quite low, the HTHS looks good, although the KV100 is a bit low. The Molygen is reasonably priced, has a high KV100, but has a high NOACK and unknown HTHS. Ravenol RSE has a great HTHS, good NOACK, and decent KV100, but is hard to find. Same with RRS but specs not quite as good. Both the HPL 10W50 and 5W50 look excellent, just have to be special ordered. Maybe if they have good shipping I would be willing to go that route. The Amsoil 5W50 also looks attractive, and NAPA right down the street is an Amsoil dealer. The Motorex oils look downright amazing with NOACK<6, and are not all that hard to find (KTM dealer). No HTHS or NOACK listed for Mobil 1 Supercar 5W50.

 

[atikovi]

BMW specs a 10W60 for some applications. Maybe try that, but how has a 1970's daily driver car not turned to dust in Mass by now?

 

[kschachn]

Just wondering, do you ever act upon any of the advice you get from your numerous posts and threads, or do you just post more?

 

[79Subaru]

BMW specs a 10W60 for some applications. Maybe try that, but how has a 1970's daily driver car not turned to dust in Mass by now?

Oil undercoating yearly, frequent washing, every couple days in the winter. Some small rust spots that need to be fixed, but nothing major, and nothing that hasn't been there for years. Also application of CRC Zinc-it on areas where the corrosion protection is gone. I have tried 10W60, the Total 10w60 was quite good, if a little thick for winter, but has been discontinued at AAP. I bought as much clearance as I could and have run through it all. Castrol 10w60 shears basically instantly, in 200 miles or so. Liquid moly 10w60, haven't tried, but is expensive and there are other seemingly better options in that price range.

 

[79Subaru]

Just wondering, do you ever act upon any of the advice you get from your numerous posts and threads, or do you just post more?

I followed the recommendation for Mobil. 1 EP for my mother's new car, or will when it arrives this week. Found out from that thread that there appears to be nothing special, or worth the price, about Ravenol DXG specifically. Also wanted to see if anyone had any advice on that engine, but it seems it's too new. If I get a good recommendation for oil for this car, or one I haven't tried yet, I will try it. Had an unusual oil filter, wanted to see if anyone knew anything about it, just incidental, because I had it in front of me on my desk, and had a second oil filter question that my friend was asking me in relation to the CAT 1R-0713, which I ended up finding an efficiency chart for that media anyway. Have read this forum for years, just never joined because I never had a question that wasn't already answered. In this case I had multiple unusual situations happen all the same week, my mother's new car, switching to winter oil in my own car, which is always problematic because of the high viscosity requirement and tendency to shear oil, and the CAT filter question for my friend. The other oil filter was just an incidental question as I couldn't find any information about it, calling the company didn't give me any information I didn't see on the box. And then information and pictures that people were happy to see relating to the GM 1.2L.
So as a summary:
1. Buick Envista: Mobil 1 EP 5W30 or Regular Mobil 1 5W30 D1G3, Ravenol waste of money. Already bought M1 EP
2. Unusual Sierra filter: No new info. Called company, no info.
3.CAT filter: No info but I did end up finding it in an old catalog, posted pictures of that in case someone searches for that info.
4. Subaru oil: Got one suggestion for 10w60, good idea but already tried it. Maybe more people will suggest an option. Otherwise I will try the Kohler 10w50 and we will see how it works.

Most of the time I can find the info I need by searching. In this case needed advice on some unusual situations, and also had information that people were curious about relating to a new engine, so I provided it. The oil for that engine has already been purchased, based on someone's confirmation that it was currently the best choice.

 

[pzev]

the M1 supercar is relatively easy to find, and can be had on sale at Napa for around $10-11 a quart at various times of the year. Per my reading it will likely be more sheer stable than the FSx2, with more PAO in the base and a stronger add pack. Otherwise for sheer stability, you might look at Amsoil SS, I've never heard reports of that oil sheering in Mustang applications.

 

[Overfill]

Just because I think you will be hard pressed for a commonplace multigrade solution, I believe I ought ask: how are you sure that the drop in oil pressure is permanent shear instead of fuel dilution? I ask because if it is caused by fuel dilution, then tons of options open up to you.

Motorcycle oils ought be blended to provide very little drop in viscosity, and would contain high SSI Viscosity modifiers. If those aren't working, you might truly be cornered.

 

[Tkonrr]

Any idea if there is excessive fuel dilution of your oil? If so, leaning it out a bit might keep your oil from thinning too much. I'm also wondering if there is an upgraded oil pump that can keep the pressure from dropping too low when the oil is hot. Ever considered a thermostatically controlled oil cooler?

 

[MParr]

Motorcraft 5W50 at your local Ford dealer, Summit Racing, or Amazon.

https://www.motorcraft.com/content/dam/ford-motorcraft/en_us/motorcraft_global/products/pdf/SAE_5W_50_Full_Synthetic_Motor_Oil/Product-Data-Sheet-5W50-Full-Synthetic.pdf

 

[JavierH19]

why does it need a 50 or 60 grade? is 40 not enough? What are the clearances.

 

[BMWTurboDzl]

My daily driver is a 79 Subaru DL with an EA71S engine swapped in. That is a 1.6l flat 4, pushrod engine, high compression (12:1-13:1ish), low tension rings, naturally aspirated, gear drive cam, long cam duration (around 305/305 advertised). Powerband is around 4000-6700 RPM, cruising RPM is around 3500-4000 usually. Does not have an oil cooler, and has large bearing clearances. Oil temp tends to run at around 102C on the highway, but can reach as high as 130C. Likes a 50 or 60wt oil. Driven 90-95% highway, long distances. In winter I tend to run M1 FS X2 5W50. Mainly because it's easy to find. Does well for cold starts but seems to start shearing or getting thin at around 3000mi. By 5000 it is no longer usable in this engine and has to be changed (hot oil pressure too low). Been thinking about trying another oil. Molygen 5W50 looks attractive but not sure if it will really perform any better than the M1. The Kohler 10W50 small engine oil is also easy to find at Tractor Supply and has good specs. Ravenol makes a 10W50, so does HPL, and there are various motorcycle 10w50s and thin 15w50s. HPL and Amsoil also have 5W50s. There is also the ZO6 Corvette 5W50, M1 Supercar. What do you guys think will perform the best, while also not being outrageously difficult to find. Here are some spec sheets:
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From these data sheets, the 10W50 Kohler Pro oil looks surprisingly good, especially for how easily available it is. The NOACK is quite low, the HTHS looks good, although the KV100 is a bit low. The Molygen is reasonably priced, has a high KV100, but has a high NOACK and unknown HTHS. Ravenol RSE has a great HTHS, good NOACK, and decent KV100, but is hard to find. Same with RRS but specs not quite as good. Both the HPL 10W50 and 5W50 look excellent, just have to be special ordered. Maybe if they have good shipping I would be willing to go that route. The Amsoil 5W50 also looks attractive, and NAPA right down the street is an Amsoil dealer. The Motorex oils look downright amazing with NOACK

Redline *mic drop*

Red Line Synthetic Oil. High-Performance

High-Performance Motor Oil

www.redlineoil.com

 

[BMWTurboDzl]

why does it need a 50 or 60 grade? is 40 not enough? What are the clearances.

He said his hot oil pressure becomes too low. It's a 40-something year old engine.

 

[JavierH19]

He said his hot oil pressure becomes too low. It's a 40-something year old engine.

Some people think they have low oil pressure when they really don't.

 

[JavierH19]

What is your hot oil pressure at idle and while driving.

 

[79Subaru]

Any idea if there is excessive fuel dilution of your oil? If so, leaning it out a bit might keep your oil from thinning too much. I'm also wondering if there is an upgraded oil pump that can keep the pressure from dropping too low when the oil is hot. Ever considered a thermostatically controlled oil cooler?

1. It fuel dilutes about as much as a typical carbureted engine, which is to say not excessively, I think the main problem is shear and heat degrading the oil. It's already about the leanest it will go without sacrificing power or starting to ping.
2. There is no upgraded oil pump, I already have the best one, and it has a shimmed relief valve. There are very few parts for these engines in the first place, even in Japan.
3. Oil cooler is so far not an option, I have considered it but it would take a lot of space, and there is no space to mount it or route the hoses. The one type of oil cooler that would work would be a water to oil plate heat exchanger, and at some point I may do that, but at this point it's not in the budget nor do I have time to be taking the oiling system apart on my daily driver.

 

[79Subaru]

What is your hot oil pressure at idle and while driving?

Here are the oil pressures with new oil and old oil: New 5w50: idle 25-30, 3000 50, 6500 70. Old 5w50 5000 mi: idle 8-10, 3000 30-35, 6500 55-65. When the oil is changed the pressures go right back to where they were before. Engine is in good condition, clearances are just set beyond what would be expected for an oil pump this small in a cold climate.

 

[79Subaru]

why does it need a 50 or 60 grade? is 40 not enough? What are the clearances.

Actual clearances are unknown. Engine was built in Japan in the 1980s. I took partially apart to inspect, looked good inside but didn't want to split the case and get that deep into it. It's a race engine, not intended to go into a street car, likely not intended to be run in cold weather. It specs a 10w50, 15w50, or 20w50 only. Going to a 5w40 or 10w40 oil gives me a hot idle oil pressure of about 5 psi or so, maybe around 2 or 3 if I have run it very hard. Which is just not a pressure I am comfortable with on this engine. It also tends to burn a lot of oil on 40wt (Oils I tried were Molygen 5w40 and Mobil 1 HM 10w40) This is an engine that spends most of its life at 4000 RPM or higher just on the highway, and is making double the power output that the block was intended to sustain, and is making 20 HP extra over what it originally made in full race trim. The shear originates from the timing gears, I believe. There is no timing chain or belt, the camshaft spins backwards of the crankshaft, and is driven by a pair of helical cut gears. The powerband is from 4000 to 6700 RPM, so it gets revved past 6000 basically every time I drive it, which means the oil temp always gets into the 130ish (Celsius) range. At that temperature, a 40 oil results in 50 psi oil pressure at around 6000 RPM. Which I don't like because any lower and I feel like damage is going to start happening. The gerotor in the oil pump is about the size of a half dollar or less. The entire thing, not just the inner gear. Only way to upgrade would be to go to a dry sump. Which I am not going to do on this car. I would rather just go for an oil in the intended viscosity range regardless of cost, and provided some examples of what I thought would be some good oils to try. I still think the Kohler 10w50 would be a good oil because of how easy it is to find and being intended for hot running air cooled engines. The Motorex 10w50 is another. I really would like to stay within a 5w50-10w50-15w50 oil. The Redline 10W50 also looks very good with 19.7 KV100 and NOACK 6. That is one I definitely want to try, that could potentially be a year round oil.

 

[mt23]

My vote for the HPL 10w50. Running it (5w40) in my 1986 EA81 subaru.

 

[79Subaru]

My vote for the HPL 10w50. Running it (5w40) in my 1986 EA81 subaru.

It looks like an excellent oil. My only concern is with difficulty of having to special order it given the frequency at which the oil has to be changed. The EA81 I used to own in an 83 Brat was quite a bit less harsh on oil, but it was a near stock, lower revving engine. While this shorter stroke EA71S is essentially maxed out as far as it will go without forced induction. If I can extend the intervals a bit without it thinning out too much, the special ordering would not be as much of a concern. How does the 5W40 do in your EA81? Any issues with shear or thinning out too much by the end of the OCI? Obviously comparing two completely different engines but from the same family. And the second question would be how do you find their shipping?

 

[Astro14]

It looks like an excellent oil. My only concern is with difficulty of having to special order it given the frequency at which the oil has to be changed. The EA81 I used to own in an 83 Brat was quite a bit less harsh on oil, but it was a near stock, lower revving engine. While this shorter stroke EA71S is essentially maxed out as far as it will go without forced induction. If I can extend the intervals a bit without it thinning out too much, the special ordering would not be as much of a concern. How does the 5W40 do in your EA81? Any issues with shear or thinning out too much by the end of the OCI? Obviously comparing two completely different engines but from the same family. And the second question would be how do you find their shipping?

Why would it have to be changed so frequently? Until you run this in your car, you won’t know how quickly it shears down, if at all.

There is a member on the board who is running HPL in heavy duty turbo diesel truck that is used exclusively for towing and has 20,000 miles on the oil without measurable shear. That oil is still in his truck.

Since you are measuring shear by the change in oil pressure, and you are driving a unique car, a naturally aspirated, high compression, high RPM, one-off, Subaru, why not try a unique oil? Nobody has experience with this engine because nobody else has this engine. You will have to experiment.

I’ve ordered many cases from them. The “special order” that you seem to think is difficult is actually quite easy. They generally get the order to you in two days. It cost 25 bucks a case to ship - might as well get a case.

Don’t forget to add the BITOG15 discount code in checkout.