Oil weight reccomendations.

[chillman88]

Hey guys,

I'm running Rotella T SAE 30 in my truck right now, but what do you guys reccomend?

I live in NY, during the winter I know I need to run a lighter oil like a 5-30.

My drive to work is about 6 minutes, my truck is warm about 4-5 minutes into the drive, but on the way home (downhill, and about 3 minutes) the truck doesn't even warm up.

I am not overly concerned about mileage, if longevity increases with a heavier oil, and I have no problem letting the truck warm up first if need be.

I drive a 1997 Chevrolet K1500 4x4 pickup with a 5.7L v8. I'm not exactly gentle with it. The user manual says 10-30. I'm just wondering if that is more for fuel economy, and if there is any benefit to switching viscosity to something a smidge heavier, like maybe 15-40?

I don't have a cat to worry about plugging, so that is irrelevant.

 

[oiltard]

Wait, you're running straight 30-grade oil?

The use of a multi-grade oil isn't just for fuel economy. It's for proper lubrication of an engine between when you start up and reach full operating temperature, which your truck never does in those distances.

 

[Rob_Roy]

5w30 or 10w30 would be fine. SAE 30 is far from ideal in NY winter weather...especially for a short trip. 15w40 would also work, but is not necessary.

 

[Rand]

when you say upto temp.. thats water temp..

I highly doubt your oil is upto temp is anything less than 10miles even in the summer.

 

[chillman88]

I meant that I don't care if I lose a couple mpg if I increase longevity of the motor.

Yes, I am running straight 30 grade (with a quart of Marvel Mystery Oil).

I normally run 10-30 or 5-30, but I JUST changed head gaskets, and wanted something thicker in case any gasket material got left in the engine, hoping it would lubricate better, might have been a poor and uneducated choice, but it sounded good at the time. I planned on switching to 10-30 at my next change, but I am weighing my options with you more educated folks. I have considered synthetic oils too.

Really I'm just trying to nail down what would be best for the longevity my vehicle. Weekends my engine gets up to temp, but not a whole lot during the week.

She has right around 100k on her now (or so I was told, pre-owned engine transplant).


And yes, by "up to temp" I meant that the thermostat opens and the coolant temp stops rising.

 

[chillman88]

ha, I was typing my reply and got 2 replies and an edit in the meantime!

Anyway, what about using a synthetic? I'm always leery of using one that pours like water (like a 0-30), but if it does its job...

In my purposes, what would be the difference between a 5w-30 and a 5w-40?

 

[Brons2]

0w30 doesn't pour any different than 5w30 or 10w30. In fact some of the 0w30 weights are actually heavier at operating temp than many other Xw30s. For example German Castrol aka "GC" 0w30 is close to a 40 wt at operating temperature.

In your case I would use dino 5w30 in your engine. If you want something more exotic, go for Mobil1 0w40.

 

[skellyman]

About any 5w30 or 10w30 would do in New York , just look for the API donut an not some SE SF elcheapo oil .

 

[chillman88]

I appreciate your replies, Three more questions for you...

skellyman mentioned "the API donut" I am assuming that is a spec certification, correct?

Second, in as simple as possible technical terms, cold weight aside, what is the difference @ operating temp, between SAE 30, and SAE 40 grade oils. I understand that 40 is "thicker" but what does that mean.

I have one other vehicle, same motor, twice the mileage, leaking badly (main seals) My neighbor said he ran an older, carbed truck (with same motor, same problems) from just over 200k miles to just under 400k miles on 20w-50 and it didn't leak (but he scrapped it because the body was gone). Is this safe for a while until I can replace the main seals?

 

[Zaedock]

Modern SAE30's are a decent 3 season oil in certain applications. I still have a few gallons of Delo SAE30 that I use in my Jeeps and daily driver's.

It's currently not ideal for best fuel economy, but it won't do any harm. I don't see a need to go thicker though. After this change, I would just stick with 5W30 as a 4 season oil in your 350.

 

[Garak]

I agree with Zaedock. You could easily run the 5w-30 year round and save yourself a lot of hassle. Whether it's a straight 30, a 10w-30, 5w-30, or 0w-30, they are all about the same viscosity range (a 30 grade) at operating temperatures. With the straight 30, you just forgo a lot of cold start protection. It certainly isn't the end of the world, though.

A 40 is absolutely unnecessary. Again, it won't explode your engine, but I've run many, many SBCs from the late 1970s to the mid 1990s with 10w-30 for fleet use. If you wanted good cold start performance with a 40, you're stuck with a 0w-40 or 5w-40 and the corresponding price increase due to being stuck with a synthetic or semi-synthetic.

The difference between a 5w-30 and a 5w-40? The former can be had for about half the price of the latter.

 

[dnewton3]

chillman88, let me show you a couple of examples in regard to this topic:

http://www.autoblog.com/2008/02/01/wisconsin-mans-91-silverado-set-to-hit-1-million-miles/

http://www.knfilters.com/million/


No synthetics in sight. No "thicker is better" oils used. Just "normal" oils at "normal" OEM OCIs.

Do not make the incorrect assumption that using a particular oil, (or the lack of using one) will automatically assure success or failure.

Proper, well controlled and practiced maintenance will assure longevity. Your truck is much more likely to live a long life due to a well executed maintenance program than it will by worrying about what brand/grade to put in the crankcase. As long as you use a properly spec'd lube, it will do fine.

I doubt you'll get the longevity such as those two extreme examples; they had long drive cycles and yours are short. But the point to understand is that oil selection is but only one topic of an OVERALL MAINTENANCE PLAN!

It would be my suggestion to use a 5w-30 year round. Because you have such a short drive cycle, I'd stick with the 5w-30 versus 10w-30 because even if the coolant is nearing full temp, the oil typically is lagging a bit in temps. I doubt the oil in the pan is anywhere near as warm as the coolant when you pull into the parking lot after only 6 minutes. Further, because of your short drive cycles, it'd stick to "normal" or perhaps even "severe" OCI cycles to keep the condensation flushed out. Because your oil is probably no where near full temp after 6 minutes, the thicker grades (xW-40) should be avoided, IMO. In short, Garak is correct; use a 30 grade.

If you REALLY want to know what choice is "better" then you'll have to run some UOA experiments.

 

[kschachn]

Originally Posted By: chillman88
Anyway, what about using a synthetic? I'm always leery of using one that pours like water (like a 0-30), but if it does its job...


If it pours like water then but is a 30-weight at operating temperature then that is good. And like was mentioned at 70 degrees or so you will never see the difference between 0W, 5W and probably 10W while pouring. But your engine can and that is what is important.

 

[rufushusky]

Why not some more mega-miles people...

http://www.millionmilevan.com/

10-20k OCIs and a few up to 55k...ekk.