5w-30 in my Ford 302 V8

[Jaymus]

Hey, guys. Well, it's getting to be like winter around here, now. I live in east Tennessee, and, well, the lows are already getting into the 20's.

Is it a good idea to use 5w-30 in my truck. It's an '86 F-150 4-speed w/ low/granny gear (NP435 tranny) and a 3.50 axle ratio. I am a Castrol GTX user in all my vehicles that I use conventional oil in. I have been using Castrol GTX 10w-30 in it. Well, I didn't know if 5w-30 would be better for it on cold starts. Or, is 10w ok to go with until it starts hitting 0 degrees outside?

I trust the 10w-30 GTX, but this is my first time ever buying 5w-30. I know it won't have as good of a base stock. I just now read that most 5w-30s sheer down to 5w-20s after 3000 miles, or at least that it is common. Is this true?

I put a tach in my truck, and at 55mph, I'm turning 2300RPM. Sounds like 3000RPM, lol.

Anyways, just looking for some input on this. I should have just stuck with 10w-30, I guess... but I just wanted easier start ups in this freezing weather.

 

[erogers]

I wouldn't worry about using 5W-30 in your 302. It will be fine. You'll have easier cold start-ups and as long as you change it regularly, you shouldn't have to worry about shearing. I've been using 5W-30 in my grandpa's 1988 Crown Victoria (also a 302) for over ten years with no problems, whatsoever. I usually switch to a 10W-30 (or 10W-40) for spring and summer and use the 5W-30 during the fall and winter. Go for it!

 

[Jaymus]

Awesome. In Mobil1's case, 5w-30 vs 10w-30, their 5w-30 is actually thicker at 100C.

But, for Castrol GTX, I read that the 5w-30 and 10w-30 have the same viscosity at 100C. So, that's one thing that made me not feel bad about going 'down' to 5w-30. It's just that it's not as good of a base stock as 10w-30. But, I change the oil in this truck every 3000 miles, or actually, BEFORE 3000 miles. Why? I dunno

 

[erogers]

Yeah, I know what you mean. I usually end up changing my oil sooner than necessary, too. It's all part of the obsession all of us BITOGers have!

 

[JohnBrowning]

Give it a try and see if you notice a difference! If the 5W30 is going to make a difference you will notice it in how much easier it cranks when cold and less valvetrain noise... I know those are not very scientific but they are easy for you to listen for! If it does not turn over any easier then it is probably not makeing any difference one way or the other...

I live in Michigan and have a mix of Tropartic 10W30 2 quart's and PP 5W30... I was trying to use up the TropArtic 10W30 I bought for the wifes car.... I did not use it on her car so I figured I would mix it in with my car's oil....It get's a lot colder her in Michigan then in TN. so I think you will be fine either way! Most 5W30's have better base stock's then their 10W30 counter part's but theya lso have more VII's so it can be a mixed bag of nut's at time's decideing wich one you want to use when you are talking dino!

 

[ewetho]

My dads 302 went 165K miles on 5W-30 before being totaled in an accident (not my dads fault) and did not consume any oil. (Ok we tried 5W-20 since it was backspec'd for the year and consumed almost 1 quart in 4K)

Use 5W-30 and be happy. Newer oil are much better than the old stuff.

 

[jsharp]

I tried one dino 5W-30 in my 5.0L and it sheared to a 20 weight in under 3K miles. That may or may not bother you and I don't know if Castrol would do the same.

Ford claims 10W-30 is good to 0F. I don't think you'd have a problem sticking with it if you chose to.

 

[Jaymus]

Well, I had been using 10w-30, but I went to 5w-30 because it's been getting in the mid-20's in the mornings around here.

I had been having a little start up clatter (maybe 1 second) and then it would all smooth out.

I have NO MORE of this. I think it is in the filter, though. I had been using Bosch filters, but last time, I got a Motorcraft filter. I haven't heard a single thing in the way of start up clatter since then.

I don't know if it's me going down to a 5w-30, or if it's more in the filter (motorcraft FL1A), OR if it's a combination of both.

And, yes, shearing to a 20 weight in under 3k miles does worry me. I plan on changing at 3000 miles or earlier, so it may not be a problem. I don't know.

 

[erogers]

I'm sure that 5W-30 does shear to a 20 weight in many engines over time. However, I think 5W-30 gets a very unfair shake if we are to assume it shears every time and in every engine. The truth is, only a UOA will determine whether it shears (and the extent that it shears) in your own engine. Let's not all just blindly follow the "5W-30 is not as good because it shears" crowd. I think we owe it to ourselves to know for sure, in each of our applications. Just my two cents.

 

[Gary Allan]

Even if it does shear ..who cares? As long as your oil pressure is good ..what real difference does it make*? The AW package is what inhibits the friction points from wearing. Then again, you probably have a fake needle if you have a gauge ..so you don't know.

*sensible conditions and restrictions apply and YMMV

 

[Jaymus]

Well, I don't want an easy shearing oil because when I am going 55mph in top gear, I am at 2300RPM. When I am going 70mph, I am at a little over 3000RPM. This is in an '86 model F-150. If normal driving at 1500RPM makes it shear, I'm sure keeping this 5200 pound truck going at 2500 - 3000RPM will definitely shear it, lol.

Also, I'm not a big lover of the 10psi per 1000RPM club. Sure, that's what it takes to be 'safe', but at 3000RPM, I hope I'm pushing 45+psi.

And, yes, I have the dummy gauge. The slow moving needle, but I keep a good eye on it, and note where the needle goes at idle when I'm cold and warmed up. Never goes anywhere scary.

I would like to get a UOA done on it. I am accepting donations

 

[PT1]

I would stick with the 10w30

 

[Jaymus]

Yeah, I think since I switched from Bosch and Purolator Pure One filters to Motorcraft, my start up chatter will be fixed permanently. That's the main reason I wanted to try 5w-30. When is 10w-30 not acceptable for cold temperatures? Is it recommended to go to a 5w-30 when the temperatures hit 0 degrees F?

 

[TallPaul]

10w30 is the way to go. 10w30 is rated good down to zero F.

 

[mechtech2]

It's not written in stone that a 5-30 will shear more/less than a 10-30.
It is a good general rule to use as low a first # as possible.

 

[Jaymus]

Well, I can agree that the lower the first number you can use, the better... for easier start ups, since start ups are the hardest part for an engine (especially the first 5 minutes).

But, I realize that when it has a higher number (10w-xx/15w-xx), it has a better base stock. This is what I have read here. A better basestock, or should I say, MORE real base stock, equals less probability to shear.

The 302 is known to be a very cool running engine. I hope I'm ok with 5w-30. I know, I know, you can't tell squat without getting a UOA. I've never gotten a UOA, but I hope to get one sometime to give me a little info on my truck.

 

[TallPaul]

Originally Posted By: Jaymus
But, I realize that when it has a higher number (10w-xx/15w-xx), it has a better base stock. This is what I have read here. A better basestock, or should I say, MORE real base stock, equals less probability to shear.

Actually, for some brands the 5w30 has a better base stock. Durablend 10w30 SL had a significantly higher amount of Group I basestock than Durablend 5w30 SL. The 5w30 may have gotten more of the higher group base oil to reduce the amount of VII needed. The main advantage to the 10wxx is a thicker basestock.

 

[gtx510]

I stopped using 30wts in my 5.0 after the oil pump stuck and sheared the pump driveshaft. This was years ago and I was using Castrol Syntec (when it first came out). But I was doing +120mph on a 100* day...

 

[nooil]

If shearing is a problem, go with straight 30

 

[hominid7]

Granted we are talking Fords here, but my 2001 Mazda owners manual says that 10w30 is good down to -13*F (-25*C) and 5w30 good down to -22*F (-30*C).

Castrol GTX has slightly less cold-friendly characteristics, in my experience, than do Motorcraft/Conoco products. Perhaps a good compromise would be a Motorcraft product in either grade.

Motorcraft 5w30 is one of the "thicker" 5w30's at operating temps.

Motorcraft 10w30 has one of the better pour point's of 10w30's at cold temps.

I get a bit of clacking on startup in the winter with both Castrol 5w30 and 10w30. I get none with Motorcraft, Pennzoil, QS, or Superflo in either grade.

Having said that, in my '89 VW Jetta, i used Valvoline AC 20w50 year-round and had no problems even when it got down to 10 to 15*F, which is as cold as it gets in my part of the world, but it was a SOHC not a DOHC engine like my current auto.