Recommended OCI hard-driven LT1? M1 0W40

pernox · May 27, 2005

Hello BITOG folks. Been lurking here for a bit now, gleaning HEAPS of valuable information, and recognizing some faces from the various Impala SS boards. Guess it's time to register and post up!

Car in question is a '95 Impala SS, pushing 90k miles, and driven under less-than-kind conditions frequently. The car's been to the dragstrip a few times, with more frequent visits coming. I see WOT at least once daily, frequently more often. The engine (LT1) revs higher than it would in stock form due to higher stall torque converter and 3.73 rear gear ratio. (stock is 3.08) It's also deceptively dirty around here in Western MA now that the snow is melted and the street sweepers remain comatose.

I got the car at 64k and switched over to M1 5W30 - performed two 3K mi oil/filter changes. I've learned a bit since then and extended my OCI to 5K with M1 10W30. I use the Ultraguard Gold ACDelco oil filter with each change.

I've recently found M1 0W40 locally and just filled up with it. I'd like to do an analysis of this oil, as it seems to give quieter startup and high-rpm operation than the 10W30 - it seems that this is what I'll be sticking with (contingent on UOA.. hopefully it will correlate with my rudimentary criteria.

) for a while, and I'd like to find an ideal OCI. $4.98/qt is a little pricey IMO, and if I can get away comfortably with >5K changes, I'd be perfectly happy to do so!

So the question is... What would be the recommended first time to send a sample in for UOA? I was planning on 4,500 miles just in case I'll only get 5K due to conditions/etc.. Any other comments/thoughts on the oil/filter combination I'm running?

Thanks!

buster · May 27, 2005

Your doing the right thing by taking a sample. I'd go about 5,000 and take it from their. If price is no problem, I'd look into the Redline 10w-30 or 5w-40 oil, if your driving the car extremely hard.

TooSlick · May 27, 2005

I'd test it after about 7000-8000 miles.... These pushrod V-8's really aren't all that hard on oil unless you plan to run drains > 10,000 miles.

TS

pernox · May 27, 2005

Thanks for the wisdom, guys!

I'm not quite abusing the car, I guess. I just tend to drive aggressively when safety allows, and do make five short trips a week. Work is less than two miles away, so... Short trips, dusty area, occasional racing, figured an analysis couldn't hurt. If the M1 can take 7,000 miles of it, awesome! But there is only one way to find out, right?

Racerjk · May 27, 2005

I switched to M1 Ow40 from a 3:2 mix of M10w30 and 15w50. I have a '95 Formula with 54k miles on the LT1. The engine seems much quiter and smoother, especially in the upper rpm ranges! I'm impressed! I'm about 1000 miles or so into my OCI.

Rockford Fosgate Fan · May 27, 2005

Glad to see some LT1 guys on the site.

I was wondering did you ever consider running running some M1 0w30 instead of M1 0w40?

shanneba · May 27, 2005

If you search through the UOA forum you will find many LT1 UOAs. (search just the subject for LT1) Patman has done well with Castrol CG 0w-30 in his LT1. One UOA was at 6200 miles and the TBN was still over 5 with 11 1/4 mile runs.

pernox · May 27, 2005

quote:

Originally posted by Racerjk:
I switched to M1 Ow40 from a 3:2 mix of M10w30 and 15w50. I have a '95 Formula with 54k miles on the LT1. The engine seems much quiter and smoother, especially in the upper rpm ranges! I'm impressed! I'm about 1000 miles or so into my OCI.

I'll second that - for as long as I can remember (when first starting out with 5W30 and subsequently with 10W30, all M1) I had a bit of a rattle coming from what sounded like the driver's side valvetrain when revving past 4,000RPM under load. I considered exhaust leaks (eliminated with header install), torque converter noise (just installed new tranny/TC), and a rattling cat (cats were left off the car during header install.) to be the culprits. Other than that, all I could think of were clattering rockers or noisy lifters.. Since switching to the 0W40, I haven't heard this rattling noise. This turns out to be a particularly good thing since the engine is seeing those RPM ranges much more frequently since installing 3.73 gearset and 3000 stall torque converter. I had actually planned out an afternoon to pull the valve covers and check the valve lash, but now it would appear that this won't be necessary.

I'm wondering, now that the noise is gone, if perhaps there was insufficient oiling to the top end of the engine? Perhaps there is an oil restriction of some sort (particle in pushrod oil passage?), and the thinner oil didn't leave enough of a coating to keep things quiet. The thicker oil, while it would have a harder time passing through any restriction that may be present, may be leaving behind enough of a coating so that when it gets where it's going (finally) it is leaving sufficient lubrication behind to keep things quiet..

...And perhaps I'm way off base and just have a failing lifter that's staying pumped up better now that the thicker oil has gotten into it.

quote:

I was wondering did you ever consider running running some M1 0w30 instead of M1 0w40?

I haven't, personally. I know DarthSS from the Impala forums and have heard him speak highly of the 0W40 more than once - I decided to give it a shot at this oil change since my local Advance Auto has started carrying it. Again, the RPMs I'm seeing now greatly exceed what a bone-stock car will get around to in normal daily driving, so I felt that some added protection was necessary. This wasn't a heavily researched decision - is there a particular outside temperature range or set of driving conditions that you feel would lead one to prefer 0W30 to 0W40? I'd like to see 200k+ on this bottom end before the budget (and the girlfriend!!

) allow for an LSx transplant.

quote:

If you search through the UOA forum you will find many LT1 UOAs. (search just the subject for LT1) Patman has done well with Castrol CG 0w-30 in his LT1. One UOA was at 6200 miles and the TBN was still over 5 with 11 1/4 mile runs.

Thanks for the tip! I'm still learning to interpret the UOA data, but by the time I'm ready to do my own I should be well versed enough for it to be purposeful.

I'll try the (Dyson?) interpretation as well, at least on the first go-round.

Sorry for the long post, wanted to get all the bases covered.

DJ · May 27, 2005

Glad to see we turned you

.

Racerjk · May 28, 2005

My gas mileage has also gone up as well with 0w40. I've driven more conservatively since has has gotten so expensive, but I think my mileage would still be higher anyway.

Racerjk · May 28, 2005

quote:

Glad to see some LT1 guys on the site.

I was wondering did you ever consider running running some M1 0w30 instead of M1 0w40?

The 30 weight M1 oils are a little too thin for my taste. I ran straight M1 10w30 for an oil change or two. It performed just fine, but I like the 0w40 and the mix I was using better. In my wife's GTP, M1 10w30 made the engine sound like a diesel.

I would try some GC if I could find it!

TomJones76 · May 29, 2005

quote:

Originally posted by pernox:
SNIP

Car in question is a '95 Impala SS, pushing 90k miles, and driven under less-than-kind conditions frequently. The car's been to the dragstrip a few times, with more frequent visits coming. I see WOT at least once daily, frequently more often. The engine (LT1) revs higher than it would in stock form due to higher stall torque converter and 3.73 rear gear ratio. (stock is 3.08) It's also deceptively dirty around here in Western MA now that the snow is melted and the street sweepers remain comatose.

I got the car at 64k and switched over to M1 5W30 - performed two 3K mi oil/filter changes. I've learned a bit since then and extended my OCI to 5K with M1 10W30. I use the Ultraguard Gold ACDelco oil filter with each change.

I've recently found M1 0W40 locally and just filled up with it. I'd like to do an analysis of this oil, as it seems to give quieter startup and high-rpm operation than the 10W30 - it seems that this is what I'll be sticking with (contingent on UOA.. hopefully it will correlate with my rudimentary criteria.

) for a while, and I'd like to find an ideal OCI. $4.98/qt is a little pricey IMO, and if I can get away comfortably with >5K changes, I'd be perfectly happy to do so!

So the question is... What would be the recommended first time to send a sample in for UOA? I was planning on 4,500 miles just in case I'll only get 5K due to conditions/etc.. Any other comments/thoughts on the oil/filter combination I'm running?

Thanks!

As far as how many miles to go before sampling, I'd just wait until the GM Oil Life Monitor tells you it's time to change.
If you don't like that idea , I'd suggest 5,000 miles or 6 months, whichever comes first.
I'd suggest checking out M1 Truck & SUV 5W40. Some prominent BITOG members have mentioned that M1 0W40 has a bad habit of shearing out of grade when it's in the LT-1, but the 5W40 is made for semi tractor applications, and should be among the most shear stable products Mobil makes.
Mobil 1 T&SUV: http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_Truck_SUV_5W-40.aspx

Racerjk · May 29, 2005

How bad does 0w40 shear?? It would still be thicker than 0w30 or 10w30 M1 wouldn't it?

TomJones76 · May 29, 2005

quote:

Originally posted by Racerjk:
How bad does 0w40 shear?? It would still be thicker than 0w30 or 10w30 M1 wouldn't it?

Probably still thicker than the next grade down.
The issue that worries me is not the viscosity change per se.
The issue for me is that an oil wasn't designed to break down like that. I would worry that the process of shearing would leave behind loose molecules of varieties that were not engineered to be in the engine of a motor vehicle.
Would the loose molecules bind to your anti-wear additives and decrease the effectiveness of those?
Would they hork up your anti-oxidants?
That's the kind of concern that I have.
To me using an oil that shears out of grade (except by design, which is another story) in my engine is like letting an untreated psychiatric patient handle payroll at my company: I'd just rather not do it.
Of course, I'm not a chemist. If Terry, Tooslick or Molakule want to come in here and tell me there's nothing wrong with M1 0W40 in an LT1 I'll gladly say I was expounding beyond my realm of knowledge. I can only speak professionally about something if it's a computer problem...

Recommended OCI hard-driven LT1? M1 0W40

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