High performance (800hp+) for winter and summer - Audi 4.0t

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Hello it’s been a while since I ran a high turbo euro direct injection car and want to ask for some advice.

Car is Audi A8 4.0 twin turbo, just installed upgraded turbos and software and about to turn up the boost, targeting 35-40psi and 800whp+.

I using German/Belgian Castrol 0w40 and live in the lovely snowy northeast (sarcasm).

Car is know for bearing wear under these power levels and I would like to improve bearing life.

Can anyone recommend me an upgrade? Should I run a 5w50 in winter and 15w50 in summer or 5w50 all year? Any brand I should look for? I used to run Rotella T6 5w40, would that be a better option? Any advice would help.
 
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I'd go M1 FS 5w50 winter and 15w50 summer. Could even go for 10w60 in the summer (Liquimoly or Motul 8100) if you want serious MOFT headroom. Rotella no longer carries gas engine specs and a thin 40 like Castrol or Mobil 1 is really pushing your luck.
 
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Since warranty is no longer relevant.

Redline 5w40. It has a high HTHS of 4.4 and isn't loaded with viscosity index-improvers.
Redline 0w40 also has a high HTHS at 4.0
Both on a 5k-7k OCI. Year round use.

The reality is that you've exceeded the design parameters of your engine and only you know how often you'll use all that power so YMMV. I mean how often are you going to be using all that power? 0-60 darts from light to light and when passing on the hwy?
 
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Is there any chance you have a way to monitor oil temps? Usually if you run too high of a viscosity, oil temps will go up. This is useful to know in situations like these where you want the maximal oil film thickness but you aren't able to play with bearing clearance like you can when you rebuild something for high power.

I'd say Redline 0/5w40, HPL supercar 0w40, Amsoil SS 0w40, or Motul 300V 0/5w40 would all be good places to start. If the engine can handle more viscosity, you can move up from there.

Also, I'm not sure if your car still has catalytic converters on it, but if it does, make sure you have a good breather system with catch cans. Don't want these high-zinc oils poisoning your cats. That and it will help a lot with oil deposits in the intake if that's an issue with the 4.0.
 
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What fuel will it run on? 50 minimum you are adding 100% more power nearly. Any alcohol fuel you will have to run a 60.

I have a strong suspicion 60 will just spike oil temp and not provide any better protection at the bearing. 60 is great for racing engines with clearances opened up to take advantage of the film thickness, but most engines don't handle it well as they come from the factory.
 
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I have a strong suspicion 60 will just spike oil temp and not provide any better protection at the bearing. 60 is great for racing engines with clearances opened up to take advantage of the film thickness, but most engines don't handle it well as they come from the factory.
Depends which fuel, they have screens that get blocked, that's the common problem.
 
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Depends which fuel, they have screens that get blocked, that's the common problem.
Not sure what the type of fuel has to do with screens getting blocked. Just get an oil that can handle ethanol if you're running alcohol fuels and make sure it's getting up to temp. No need to change viscosity.
 
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Not sure what the type of fuel has to do with screens getting blocked. Just get an oil that can handle ethanol if you're running alcohol fuels and make sure it's getting up to temp. No need to change viscosity.
So if not a higher viscosity to help mitigate fuel dilution, what oils "can handle ethanol"?
 
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So if not a higher viscosity to help mitigate fuel dilution, what oils "can handle ethanol"?
Most any top tier oil from HPL, Amsoil, Motul, Redline, M1, etc handles ethanol just fine as long as it's getting up to temp (so the ethanol evaporates out). Fuel dilution is a driving style problem.

If you have to move up in viscosity to handle fuel dilution, your bandaiding the real issue. Either the tune is too rich or you don't drive the car hard/long enough for the oil to get to temp. Now you've compromised cold start performance and outright protection.

It's best not to guess and to go by oil temp/pressure.
 

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Hello it’s been a while since I ran a high turbo euro direct injection car and want to ask for some advice.

Car is Audi A8 4.0 twin turbo, just installed upgraded turbos and software and about to turn up the boost, targeting 35-40psi and 800whp+.

I using German/Belgian Castrol 0w40 and live in the lovely snowy northeast (sarcasm).

Car is know for bearing wear under these power levels and I would like to improve bearing life.

Can anyone recommend me an upgrade? Should I run a 5w50 in winter and 15w50 in summer or 5w50 all year? Any brand I should look for? I used to run Rotella T6 5w40, would that be a better option? Any advice would help.
With the money at risk you have - contact High Performance Lubricants (HPL)
 
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Most any top tier oil from HPL, Amsoil, Motul, Redline, M1, etc handles ethanol just fine as long as it's getting up to temp (so the ethanol evaporates out). Fuel dilution is a driving style problem.
Fuel dilution is the problem with alcohol fuels. How do these particular oils tolerate that better than others?

And which Amsoil or Motul products? There are more than one.
 
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Fuel dilution is the problem with alcohol fuels. How do these particular oils tolerate that better than others?

And which Amsoil or Motul products? There are more than one.
It's not a problem if the oil gets to temp and the engine has a proper crankcase breathing system.

Probably most of them, but Amsoil SS and Motul 300v if we're talking top tier.
 
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It's not a problem if the oil gets to temp and the engine has a proper crankcase breathing system.

Probably most of them, but Amsoil SS and Motul 300v if we're talking top tier.
I see. What is it about those products that is better for alcohol fuels, especially if the alcohol is not getting into the oil?
 
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I see. What is it about those products that is better for alcohol fuels, especially if the alcohol is not getting into the oil?
Oh the alcohol is definitely getting into the oil, just like gasoline gets into the oil in every car/engine. I'm not a chemist or an expert in tribology, so I can't break down why synthetic base stocks are superior in how they react with alcohol. I can tell you from personal experience with well over 100 ethanol powered, aftermarket-tuned turbocharged vehicles (Making anywhere from 400-1100whp) that do extremely well on 5w40 oils and don't need some obscene increase in oil viscosity to counteract the supposed viscosity loss from alcohol (according to oil pressure and temperature). We of course would open up the bearing clearances in the ones we built to make power, so those would run 5w50.

Condensation is also a huge issue in ethanol powered engines, as alcohol is hygroscopic. You can watch the oil's water content change from startup to operating temp, especially here in the cold midwest. Cold start an ethanol car over and over, and it'll straight up turn the oil to milkshake colored. Methanol is even worse. Let that thing get nice and warm and poof, all the water disappears. Ethanol has a lower evaporation temperature than water. It's not staying in the oil if the oil is up to proper operating temperature (220F+).
 
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To be noted, we would recommend 5000 mile changes on most of these vehicles, mostly because ethanol does leech ZDDP out of the oil and into the breather system, and obviously we didn't want these highly loaded engines depleted of the proper additive package to keep them alive, especially if they were running journal bearing turbos.
 
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