Oil recommendation for 2.3L Stroker Evo 8

[standard235]

Hey all, long time lurker, first time poster. I have an 03 Mitsubishi Evo 8 with a 4G63 based 2.3L Stroker built by RS Motors back in 2013. Car was ran on a 10W40 when originally built, believe it was Redline. Currently, the car has been on a diet of 20W50 VR1 in the summer and then Rotella T6 to clean in the cooler months before storage. Boost is upwards of 40+ on a Holset HX40 with a billet 60mm compressor from KTS, E85 fuel, makes somewhere in the area of 700whp. Revving the car to 8200. Eagle crank and rods, Wiseco HD pistons. Bearings are saying prayers for oil film for sure.

All of this being said: Should I continue running this car on VR1? Something better for the money? I change it fairly frequently due to fuel dilution, but hopefully once it gets fresh rings and bearings this winter, I can do slightly longer OCI's. Opinions/suggestions welcome. Considered something like a Euro 0W40 synthetic, but the lack of ZDDP compared to a race oil is worrisome on a journal bearing turbo with high thrust loads present, as well as the RPM involved. Aggressive cam profile on the Kelford 280's too.

 

[racer12306]

This is such a specific use case.

If you're dumping it pretty regularly, it's probably worth staying the course since the economics get a little rough if you start dump $12-15/qt oil out too regular.

If you're having new bearings put in by someone, might be best to get a viscosity recommendation from the place doing that. If you get the dilution taken care of, I'd reach out to @High Performance Lubricants for a product recommendation. Great people and quality products. I'm sure they have an oil that would suit this engine well.

 

[KEVINK0000]

In my view, 20w-50 VR-1 is much better for your application than any Euro 0w-40. Don't go backwards.

Redline and Mobil 5w-50 are held up high in crazycar circles. But, I suspect a short OCI will always be best for you, so it is likely VR-1 will always be the best choice

 

[standard235]

@racer12306 I'll be doing the rebuild in-house. I will likely set clearances to run a 50wt with ACL's Tri-Metal bearing STD+0.001" on rods and mains both. The economics of dumping it less frequently and running a "better" oil would be nice. Engines aren't cheap, so the idea of losing an engine being cheap on oil changes is not something I like the idea of.

@KEVINK0000 That's kinda my thoughts. The VR1 5qt jug of 20W50 on Amazon is pretty inexpensive, and a frequent change is going to be a necessity on E85 with the rings gapped for the boost I'm running.

I suppose one thing to note is that this car does get a lot of street miles on it considering the build. Probably 250mi a week in commuting to work plus getting out to play on weekends. Truthfully, I'm going to be looking into a stock geo rotating assembly to get rid of some of the side loading and allow me to rev the car out more.

 

[A_Harman]

The Holset HX40 has been holding up for you? What kind of EGT's are you running? Diesel turbos don't like running over 1400F.

Don't pick a high ZDDP oil thinking you're dealing with oil film thickness on journal bearings. The number you are looking for there is HTHS.
ZDDP is good for high unit-loading locations like sliding cam followers and oil scraper rings. If the Mits engine has roller cam followers, ZDDP is not very important for the cam interface so much as its good for the needle rollers and roller axle.

Have you been doing used oil analyses to understand how bad your fuel dilution problem is? How much has the viscosity been breaking down versus the miles or number of track hours you have been running? How hot does the oil get when you're racing?

I'm more of a fan of synthetic oils for high-boost spark-ignition engines. Redline 10w40 is plenty stout. I remember reading on Redline's website someplace that POE oils are better at resisting fuel dilution than other types. AMSoil Dominator, Z-Rod, and AMO are nearly bulletproof in terms of temporary shear ratio.

 

[KEVINK0000]

Yeah it's not the ZDDP alone that makes VR-1 a good choice for this engine. When people think of ZDDP they think of valvetrain. For this engine, I am thinking ring pack, cylinder, and piston skirt wear.

20w-50 Vr-1 HTHS has been reported in the high 5s, but I can't find on their site. I think people have contacted them to get the number.

Regardless, for the $$ it will still likely be the best choice for HTHS and other attributes.

But the real winner, is the Valvoline 20w-50 Daily Protection, at 13 (!) HTHS. I thought this was a typo years ago, but the newest PDS has the same number.

I still think you will have to dump this engine's oil frequently, and will want to.

The cost of VR-1 puts it into the easier to stomach short OCI category.

 

[standard235]

The Holset HX40 has been holding up for you? What kind of EGT's are you running? Diesel turbos don't like running over 1400F.

Don't pick a high ZDDP oil thinking you're dealing with oil film thickness on journal bearings. The number you are looking for there is HTHS.
ZDDP is good for high unit-loading locations like sliding cam followers and oil scraper rings. If the Mits engine has roller cam followers, ZDDP is not very important for the cam interface so much as its good for the needle rollers and roller axle.

Have you been doing used oil analyses to understand how bad your fuel dilution problem is? How much has the viscosity been breaking down versus the miles or number of track hours you have been running? How hot does the oil get when you're racing?

I'm more of a fan of synthetic oils for high-boost spark-ignition engines. Redline 10w40 is plenty stout. I remember reading on Redline's website someplace that POE oils are better at resisting fuel dilution than other types. AMSoil Dominator, Z-Rod, and AMO are nearly bulletproof in terms of temporary shear ratio.

The HX40 has been excellent. No clue on EGT's as the manifold currently doesn't have bungs for tc's. I will be trying to get these added this year to aid in catching injector/coil issues. I know I had one injector flowing heavy judging by the plugs and the coloration on the manifold changing on the other 3 tells me they were definitely spicey at times. I do target 0.78 lambda past 20psi and taper in from 0.88 lambda at atmospheric pressure.

I've only ever heard of ZDDP being referenced in regards to turbo health. This is actually extremely important on smaller frame turbochargers that are being pushed hard. The high shaft speed/high thrust load from high boost is hard on a cartridge with a small thrust surface area to support the load. This is why Forced Performance used to have a chart of high ZDDP oils that were required to run in order to have any sort of warranty.

As for the fuel dilution, I do think it's partially due to the engine being tired. I haven't done a leakdown, but it's breathing much more through the catch can than it was 2 years ago. Fuel system issues enough to knock out a MLS head gasket pretty dramatically also probably caused some other issues.

Race cars as street cars is such as fun time.

 

[Cujet]

VR1 syn is a robust oil and can handle the loads. Also consider M1, 15W-50 and M1 20W-50 V-Twin. Many of us turbo guys found the 20W-50 harley oil was spectacular as a turbo engine oil. High thermal stability, high HTHS and zero oxidation on turbo parts.