Motul 10w40 vs 20w50

[samuel082799]

I have a 2005 subaru outback xt with an fresh built motor.

 

Je 99.75 Forged pistons

Brian crower forged rods

Sti nitrated crankshaft

11mm oil pump

King rod bearings clearance: 0.038mm

Stock clearance king main bearings

 

I think that is all the important information. Engine has 2000 miles on it, I used motul 10w40 break in oil for the first 3 oil changes (cam break in, 50 miles, 500 miles). After 500 miles I put motul 300v 10w40 in it.

 

Outfront did my machine work and they recommended either 10w40 or 20w50, and motul is there brand of choice.

 

Hot idle on my car after doing some spirited driving is at 12-13 psi oil pressure. Just cruising its up around 15-17 psi. I would like to see these numbers a little higher, especially once I start really beating on the car.

 

I'm thinking of switching to running valvoline vr1 20w50 for a couple reasons.

1. Higher oil pressure (not sure what, but maybe someone could give me a ball park)

2. Cheap and I can get it at my local auto parts store vs motul which is like $40+ and I have to find it online.

 

I know there are alot of oil threads out there, but I want to know for my particular situation if it would be beneficial to switch over to vr1. If there will be no ill effects of running 20w50 vr1 ill do it just because of the accessibility.

 

Thanks

 

 

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[boxkita]

20w50 is really thick. did you tell them its a road car? That oil rating sounds like really loose tolerances with a long warmup time (3-5 minutes)

5w30 is stock. with stock clearance main bearings there's not much call for anything more than stock oil. You should clarify with them to be sure.

 

The motul brand has more additives for reducing friction. I'm guessing the conversation about oil didn't get round to the topic of cost, did it?

 

I run a turbo diesel 15w40 oil with added zddp. This was known up-front, because a spec'ed a loose engine for high rpm endurance events. This is not a normal spec.

[samuel082799]

20w50 is really thick. did you tell them its a road car? That oil rating sounds like really loose tolerances with a long warmup time (3-5 minutes)

5w30 is stock. with stock clearance main bearings there's not much call for anything more than stock oil. You should clarify with them to be sure.

 

The motul brand has more additives for reducing friction. I'm guessing the conversation about oil didn't get round to the topic of cost, did it?

 

I run a turbo diesel 15w40 oil with added zddp. This was known up-front, because a spec'ed a loose engine for high rpm endurance events. This is not a normal spec.

 

I had the conversation a while ago, but I took notes during our talk. I remember telling them it was a street car that would see the track on occasion and do canyons and autocross frequently. Its not a daily so the warm up doesn't really bother me. The conversation didn't mention cost, because that's not my main concern as much as protection and acceptability.

 

I took my engine to them to get the cylinders bored and resurfaced, and then they told me all the parts, and tolerances I should use on the engine for what my goals are. They told me to do stock crank tolerance bearings and +1 rod bearings.

 

If i remember correctly I told them boost would be around 20psi, and redline at 8000 rpm. My redline is not that high right now because there is no point with stock turbo, but the heads are built for it, and the rotating assembly is balanced.

 

I'm just wondering if the 10w40 is going to provide enough protection under hard operation, and if this would warnt running a 20w50 oil.

 

I know of some people who run 10w40 on the street and switch to 20w50 when they go on the track. My guess is that is why he mentioned 20w50.

 

Is the psi im seeing with 10w40 normal for an engine with these clearances? I don't know what the oil pressure was stock, so I have nothing to go off of.

 

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[boxkita]

idle seems ok.

 

you built for 8000rpm & 20psi but run a stock turbo and on the street? yikes. motul is your friend. running other oils means adding zddp at every change which balances out the motul cost.

 

running race oil on the street is going to cause slot of wear on your engine. it takes a long time to get warm and it needs to stay warm. oil change intervals will be more often and it will likely discolor faster although the motul should be less frequent than the vr1.

 

unless you did the valvetrain and have a really good tune, 8000rpm is going to be a pipe dream. finding a turbo that will support that as well as a transmission is going to be problematic. 8000 rpm on track is going to be expensive no matter how you slice it.

 

In autox you'll be in 2nd gear preferably on boost for your entire run. You might get 3rd for a brief section unless you can keep the power band wide enough to use all of 8000rpm. I redline at 7000 which brings 2nd to about 65mph. I just banged on the rev limiter instead of shifting.

 

Regardless, if you don't want to use motul, i'd look beyond the advertising for an oil that doesn't break down under heavy load, has lots of detergent and anti-friction additives. The 10w40 is probably ok for the street. If you decide to track it (whatever that means), I'd get an engine block heater for warming the oil before starting 20w50. Sgt.Gator uses an external warming system for his racecar that circulates and heats the oil to operating temp before starting, otherwise it'd be a dry start.

 

If you don't have a tuner, I'd start shopping for someone who has experience with high rpm track subaru. Look ip Mark Jager. He may still run his sti that outfront built for him. It was a v4 block with lots of custom features.

[samuel082799]

idle seems ok.

 

you built for 8000rpm & 20psi but run a stock turbo and on the street? yikes. motul is your friend. running other oils means adding zddp at every change which balances out the motul cost.

 

running race oil on the street is going to cause slot of wear on your engine. it takes a long time to get warm and it needs to stay warm. oil change intervals will be more often and it will likely discolor faster although the motul should be less frequent than the vr1.

 

unless you did the valvetrain and have a really good tune, 8000rpm is going to be a pipe dream. finding a turbo that will support that as well as a transmission is going to be problematic. 8000 rpm on track is going to be expensive no matter how you slice it.

 

In autox you'll be in 2nd gear preferably on boost for your entire run. You might get 3rd for a brief section unless you can keep the power band wide enough to use all of 8000rpm. I redline at 7000 which brings 2nd to about 65mph. I just banged on the rev limiter instead of shifting.

 

Regardless, if you don't want to use motul, i'd look beyond the advertising for an oil that doesn't break down under heavy load, has lots of detergent and anti-friction additives. The 10w40 is probably ok for the street. If you decide to track it (whatever that means), I'd get an engine block heater for warming the oil before starting 20w50. Sgt.Gator uses an external warming system for his racecar that circulates and heats the oil to operating temp before starting, otherwise it'd be a dry start.

 

If you don't have a tuner, I'd start shopping for someone who has experience with high rpm track subaru. Look ip Mark Jager. He may still run his sti that outfront built for him. It was a v4 block with lots of custom features.

 

I'm taking the build one step at a time, im eventually going to upgrade to a blouch 1.5xtr twin scroll. My heads have Brian Crower 272 cams, BC valves, and double valve springs, with titanium retainers. I switched to a b25 head that uses the solid buckets instead of the shimed buckets, which are better for higher rpm. So the heads are good for it, how often will I rev it out to 8000? Not to often but its there if I need it.

 

I do my own tuning, and im running 18psi right now with stock intercooler, but my timing is way low, so it doesn't knock. Im upgrading to a grimmspeed tmic and switching over to ethanol so the car will be safer at those levels. After that im going to fabricate a cai, and cat back, then save up some dough and buy the turbo and header, and modify my downpipe for twin scroll. Then in theory it will be done and I can run up to 25psi and hold 20 to redline, from what I've seen others doing.

 

I think I'll just stick with the motul for now, until I can find a more convenient alternative. I was just concerned my idle pressure was a little low

 

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[boxkita]

a fmic is going to work better.

 

on the 5mt, you won't be hitting 8000 very often. The gears will fail.

 

best of luck