Hey guys,
As I am now due for my first oil change since I bought my rig, it has got me thinking and searching around the boards for what oils everybody is using.
My rig currently has Maxlife in it which I am going to stick with, however the weight is 10w40 and I have now read in multiple spots how 10w40 is not recommended and could easily gunk up the motor and components based off of them having to mix oils and add things to reach the 40 level. I know that 10w30 is recommended, but I am curious if it is the best choice in the hot temps of Texas, especially when under the rigors of offroading in Texas heat.

Out of my own curiousity, What are your guys' opinions on the subject? <img src="/forums/images/graemlins/kewl.gif" alt="" />

I had asked the same a while back, and got mixed replies... but, here's what I've noticed so far:

I thought I would see a slight drop in oil pressure when I switched to the 10-30. I didn't.

I have used Castrol GTX 10W-40 in my rig for over ten years, and my last change I went with the GTX 10W-30 . Used to be when I changed out the 40, the oil was NASTY looking dark brown and smelt bad. I guess I got used to it that way.

Now, judging by what I see on the dipstick, after 500 miles on fresh 10W-30, that oil is still pretty "golden", NOTHING like what the 40 looked like after the same amount of time.

I'm stickin' with the 30 .

Have read a little on this subject, and most believe that most of your engine wear happens at start up.
Therefore it is recommended that you go with a 5W-30 or even a 0W-30.
My vehicle is pretty new, so I went with Mobil 1 5W-30(can't do much better than M1).
However, if your vehicle is older, it may be harder to justify the expense of M1.
If you like to read, try bobtheoilguy. Think that's the site. Tons of info on oil.

Cool, thanks for the site, I will check it out! <img src="/forums/images/graemlins/cheers.gif" alt="" />
Maybe I should go with a 5w30 as the 5 is the cold, it wouldn't hurt in Texas, and when I am up in the mountains this winter it would be good. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Lots of folklore on this subject. The small print is that the 2.8 has a small chamber, gear impeller pump. In temps like you experience in Texas (I lived in Arlington for 5 years), and with a pushrod OHV engine, you might be better off with 20W-50. No overhead cam mobility to worry about, but with that tiny chamber pump you need raw viscosity and body in an oil which will fill the gap of wear, both in the pump and crank bearings. I've had Blazers and one Jimmy go past 250K with 2.8s massaged with Castrol or Valvoline 20W-50, didn't leak a drop or smoke ( except for two with bad valve guide seals). G'luck...Cal

20W50 is what I was actually thinking before I even posted, I was just worried 50 was going to be too heavy. I ran 20w50 in my 91 GMC Syclone as it was recommended and I never had a problem, just didn't want to get something too heavy.

How would it perform when I go to the mountains this winter, maybe a 15w50 for a compromise? <img src="/forums/images/graemlins/cheers.gif" alt="" />

Doesnt it also have a lot to do with the type of enviroment that you are in?

I use Castrol 10w-40, course I havnt used anything else before. But it seems to always be the same color...course i think it is now burning oil <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/confused.gif" alt="" />

In general, recomended engine oil viscosity varies on external temperature and mechanical stress put on the engine (like towing). Newer cars have smaller oil passages and tighter tolerances, and have switched to lighter oils. Some are not "synthetic only" or you void the warrantee.

I use Wal-Mart 10w40 in the Amigo, 177k miles.
WHen I switch to 10w30, I burn more oil.
Works fine, even in Dallas winters...though it's a little sluggish in the winters cranking over. But that's mostly due to the battery.

hey Cure actually the 30 in 5w30 is when it is cold. The oil gets thinner as it gets hotter. Thats why you have tons of oil pressure cold. I personally ran castol 20-50 in my trooper with a 2.8. When your wheelin you break oil down real quick. i use castrol 20-50 now in my Xj and love it. you do lose gas mileage so be advised. the 20-50 does slow things down since it is so thick. i seen a 2 mpg diff. in my daily driver going from 20-50 to 5-30 <img src="/forums/images/graemlins/confused.gif" alt="" />. oh well i dont daily drive my rig though so thats another factor to look at. <img src="/forums/images/graemlins/cheers.gif" alt="" />

The 10W-40 issue goes back to issues GM had in the mid 80's.

About 10 yrs. ago I wrote Castrol, Valvoline, Quaker State and Pennzoil a letter on this matter. The factory service manual for the '95 Rodeo says that using 10W-40 can cause premature engine wear. Pennzoil and Castrol responded. They both said their 10W-40 would not harm my '95 Rodeo. I wrote 2 letters to Isuzu asking them to explain their stance and heard nothing from them.

I don't doubt that 20 yrs. ago it may have been an issue. I suspect the problem has since been solved.

I don't think that 10W-40 in itself is the issue, but what is the proper weight oil for your yr/make/model.

On another forum, a tech named Jake swore up and down that 5W-30 was the ONLY oil to use in the 93-97 6VD1 V-6 3.2 liter motors. Ambient temps. were not an issue. You simply use 5W-30 year round whether you live in Phoenix or North Dakota.

I've noticed that with 5W-30 in my '95 Rodeo, things are a lot quieter underneath with the motor idling.

An interesting topic no doubt.