Oil Suggestions, E85 and WOT blowby...

[KirbyK]

I have a 11.8 CR 60k mi stock shortblock LT1 with heads and custom cam that is spec'd and tuned strictly for E85 only. I have a slight puff from the breather at idle and at high RPM (over 400)at WOT it starts to smoke a little blue out the back, and a little oil residue on the exhaust tips, but at idle and low RPM/normal driving, it doesn't seem to burn anything, exhaust tips stay completely clean. As far as oil system, I have a Melling Select pump with 70psi high pressure spring, and 6-qt Canton Road Race pan. Oil pressure even when trying 5w30 has never been below about 45 psi hot idle. Coolant temp never gets above about 195 even in stop and go city 95* heat, running stock 185* t-stat.

So I have 2 questions:
1) What type of oil is recommended for E85 use? I know a more frequent oil change interval is preferred, but what is the best type? My Harland Sharp roller rockers recommended a high ZDDP content oil, so should I use VR1, diesel, other?

2) What grade of oil would be best? I assume since is a stock block LT1, with 60k miles that bearing clearances are still pretty tight, however there is the blowby issue as well. Would a thicker high temp weight oil help that out? Such as 15w40 or 20w50?

 

[addyguy]

I think a good, general 'catch all ' rec would be a HDEO 10W-30 like Shell Rotella.

If you're getting ood OP with a 5W-30, no need to go to 40-weight. Only reason for the 10W-30 rec is that thinner conventional HDEO are 10W-30's, not 5W-30's.

How much do you drive this beast? What's it in?

 

[A_Harman]

5w30 Redline. Ester oils are supposed to be more tolerant of fuel dilution issues related to the use of alcohol fuels.

 

[KirbyK]

Ok, so conventional Rotella T 10w30 is a good oil to use in this application? I always assumed the ethanol can be a little rougher on breaking down the oil quicker than gasoline, and have heard of using diesel oils due to holding up better to fuel contamination? Redline I know is good as well, but Rotella is a LOT cheaper, especially if changing the oil about every 2500 miles. Although being a full synthetic it may also last longer?

On my last oil change about a week ago I experimented using 20w50 VR1 Synthetic, due to the high ZDDP level, WOT blowby, 95* daily temps, and the fact that my local Autozone mislabeled the synthetic 20w50 VR1 at the conventional price ($4.79/qt) I figured I would try it out. My oil pressures are now higher (obviously) about 65 psi hot idle, 75 highway cruising, 85 cold startup. Should I ride this thicker oil to the next change, or should I go ahead and dump it for 10w30 Rotella?

 

[KirbyK]

Originally Posted By: addyguy

How much do you drive this beast? What's it in?


It is only a nice weather car, it's in a 1995 TransAm. I also autocross a few times a year as well in it, setup for handling, not drag.

 

[disturban]

I would run some MMO in the gas tank every time you fill it up, that will help lubricate the upper cylinders, prevent corrosion in the fuel system it's self and it also can stop mild blow by because it can help seal the rings.

 

[A_Harman]

Originally Posted By: KirbyK
Ok, so conventional Rotella T 10w30 is a good oil to use in this application? I always assumed the ethanol can be a little rougher on breaking down the oil quicker than gasoline, and have heard of using diesel oils due to holding up better to fuel contamination? Redline I know is good as well, but Rotella is a LOT cheaper, especially if changing the oil about every 2500 miles. Although being a full synthetic it may also last longer?

On my last oil change about a week ago I experimented using 20w50 VR1 Synthetic, due to the high ZDDP level, WOT blowby, 95* daily temps, and the fact that my local Autozone mislabeled the synthetic 20w50 VR1 at the conventional price ($4.79/qt) I figured I would try it out. My oil pressures are now higher (obviously) about 65 psi hot idle, 75 highway cruising, 85 cold startup. Should I ride this thicker oil to the next change, or should I go ahead and dump it for 10w30 Rotella?


Keep the 20w50 VR1 Syn in it for the summer.
If you really want to know what's going on with the oil, take an oil sample and have it analyzed at 3000 miles. Check for viscosity, fuel dilution and TBN at that point, then decide what to do. Since you're running E85 all the time, you're stressing the oil differently than almost anybody on this board has experienced. Overall, you will burn about 30% more fuel than if you were running gasoline, so it would be sensible to reduce the OCI by 30%.

 

[KirbyK]

So I shouldn't be concerned about the oil pressures being high or the thick oil for the next 2000 miles or so then?

I'll pull a sample at about 2000 miles or so and post results, then see what you guys think then.

 

[dailydriver]

The much vaunted on this site Rotella T6 5W-40 is another possibility, for not much more than the Rotella T, price wise.