krb90

At the risk of going off on a tangent, I have to say I really don't understand this. I mean, 20w-50 is 20wt oil....5w-30 is 5wt oil. Who would use 5wt oil? Tolerances would have to be really really tight to justify that. I've seen 5w-30 recommended in newer cars, but I still don't have my mind wrapped around it totally. I mean that is really thin. I would never use it in my older vehicle. Maybe this is best left for another conversation?

91Toyota

How much did it cost you?

DupermanDave

I havent bought it yet. Im stopping by the parts store tomorrow. Autozone lists one on their site (that's in stock) for $3.99

There's also some higher quality ones for $15. I might go with a higher quality one.

trbizwiz

I thought these trucks were supposed to have 5w30 oil

DupermanDave

They're also not supposed to smoke on startup.

krb90

5w-30 maybe when they're brand new. And honestly, alot has to do with temperature of your area too. Colder climates need a thinner oil. I understand it to be the "thickness" of the oil at startup. Alot of guys here are in Canada, Alaska and other norther/cold climates. You can make an arguement there that I will accept. It doesn't get that cold here, and it doesn't get that cold on the west coast, as I see others are from. And I mean routinely starting your engine at 0-10 deg F or below. Otherwise, I would jump to 10w-30/40 or better for an engine with wear 15w-xx or 20w-50 which I run in my 200,000+ '90 model.

Or I could be wrong......I haven't spun any bearings though.

DupermanDave

I just went out and checked my oil levels. They look normal now. Since switching to the 20w50 there has been significantly less oil being burned.

Still unsure about PCV valve. I'm going to unplug it again tonight and startup the truck when I go home and see if it smokes.

91Toyota

Bought a new PCV valve and drove like 60 miles...don't know the oil level yet...but I think its burning oil because I used a synthetic blend oil on initial breaking in of the engine...so the rings might not be seated yet...although I have almost 2k miles on the rebuild. lol

DupermanDave

I used full synthetic after I did the head job. I'll have to clarify.

I added regular oil, 10w30, with a quart of risoline oil additive. After the first few hundred miles, I drained the oil and then added fully synthetic oil, 10w30 as well. that stuff burned up fast.

I removed the PCV valve again before I went home. normally when I leave work it smokes bad. This time...nothing. Good sign. Maybe the PCV valve is plugged up so bad that it's causing pressure to build inside the crankcase and causing oil to burn.

91Toyota

Possibly could be! I hope it works out well for you! If I need a valve job I'll put some more ponies on my baby!

mmcpeck

20w-50 isn't a 20wt oil, it's a 50wt oil, it's only 20wt for a short period of time, and I know I wouldn't want a thick 20wt trying to run through my engine when it was "cold", and I definitely wouldn't want a 50wt in there when it was hot, it doesn't flow quick enough to get to the places it needs to be quick enough. That stuff will kill an engine.

A 5w-30 isn't an 5wt oil nearly ever, it has some characteristics of a 5wt oil when cold, but for the most part as soon as it gets some heat it's a 30wt oil, and that will flow nice and easy to everywhere it needs to be when hot, protecting everything.

A lot of new cars spec either 0w-20 or 5w-20, and they are high revving little 4 cylinders.

It's your machine so do what you want, but 20w-50 isn't good for anything.

krb90

I disagree that is isn't good for anything, or they wouldn't make it.

20w-50 is 20 weight oil. It's called multi-viscosity, not multi-weight (although it is mistakenly referred to as such). When it gets hot, it has the viscosity of 50wt oil at the same temperature. Same for 5w-30. It's a 5wt oil and, as you describe, has the viscosity of 30wt oil when hot, at the same temperature..

Now, 20wt oil at room temperature or hotter has a lower viscosity than 5wt oil does in the freezing cold. That's why you use 5w-x in Alaska and in other cold places. 20wt would be too viscous at that low temperature. Where I live, we have extremely few, if any, nights that drop below 0 deg. So I can use a heavier oil. I'm not saying heavier is better, but it withstands heat better. And when everything is at operating temperatures, the 20w-50 is less viscous than 5w-30 is when it is cold or cool.

5w is specified because of the much tighter tolerances engines have than they did 30 years ago, not because we know any better. The molecules of oil are smaller (which is where we get "weight") and are able to fit into tighter places. On an engine with some wear, parts are a little looser, and the smaller molecules, while able to get into the areas, don't necessarily fill all the "gaps", and at hot temperatures, is as runny as water and doesn't "cling" as well.

So what I mean is that with an engine with alot of miles, it's ok to use a heavier weight oil. Now, granted, we are examining this at a molecular level....it may really not make much difference. And the real fact is that it's possible that nobody knows the real answer. I know I've never, in any vehicle I've ever had, had to do anything in the bottom end of the engine.

One thing I will say is that heavier weight oil is harder on your oil pump (never had one of those fail either though). You'll typically get higher oil pressure too.

I may have just gotten lucky over the years....

91Toyota

Thought the w after say 10w-30 was for "winter"???

DupermanDave

This is pissing me off and baffling me. I started the truck today with no messing around with the PCV valve. I thought, "if it's the PCV valve, I should leave it plugged in and see if it smokes on startup. If removing it the previous startups caused it to not smoke, then leaving it alone will cause it to act like it always did."

So I left it alone, and was right about to drive to the auto store. NO SMOKE!!! Still using the old PCV valve.

91Toyota

Jeez...did you buy one anyway? I also still have smoke...oh well. Probably from the rings...

DupermanDave

I didn't buy one, but I was going to. I had a lot of things to do today (my day off.) Never got around to it. I literally spent all day running errands and looking for an apartment.

DupermanDave

Still smoking. Wonder if it IS related to a bad valve job.

I'm still not convinced it's the piston rings, just because if it was, you'd see clouds of smoke behind you as you drive. That's why I havent made the compression test a higher priority.

Would you say your smoke is an oil burning smoke? Or a sweet, coolant-burning smoke? Because mine is definitely an oily smoke. Mine isn't coolant burning at all.

Should it be a bad valve job, I'll just ignore it until I get an RV head and cam. I'll get new valves with that from engnbldr.

DupermanDave

So you replaced the PCV valve and it's still smoking?

I cleaned mine out today before I started it up (used carb cleaner) and it didn't smoke. I wonder if it's the cold weather doing something to the truck.