Single grade vs multigrade HD oils

[redtan819]

Can anyone explain the difference between a single grade HD (30/40) oil and a multigrade (15w40) oil.

I'm looking for a better oil for my piston slap riddled car, and I have been advised to do an AutoRX cleaning and then apply a nice HD oil afterwards. I was looking at either the Rotella HD 15w40 or a Penzoil HD30/40.

Multigrade oils have different viscosities depending on the operating temperature. So a 15w40 oil is 15 at cold startups and 40 at operating temps. So with my limited knowledge of oils, this means that a single grade HD30 oil means its 30 weight all the time no matter what the temp is?

Is this correct, if not what is it.

Thanks for the help.

 

[G-MAN]

I really don't think a HDEO is going to help your piston slap. You need an oil with a high moly content and/or a high ester content.

Do the Auto-RX treatment and then get Castrol Syntec, Syntec Blend, or GTX Startup. I've uploaded a vid clip of my 3.4 to YouTube and I'll post it as soon as it finishes processing. You'll see just how quiet mine is. Yours may not wind up being as quiet as mine, but mine was pretty loud and now after Auto-Rx and running Syntec Blend there almost no discernible piston slap.

 

[redtan819]

Cool, so are these oils (Castrol Syntec, Syntec Blend, or GTX Startup) high in ester and moly content then?

Are there any other ones like this?

And on the autorx site it says not to use a synthetic oil after th first stage.

 

[G-MAN]

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Cool, so are these oils (Castrol Syntec, Syntec Blend, or GTX Startup) high in ester and moly content then?

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Don't use any of these oils during the Auto-RX treatment or rinse. Use regular Castrol GTX.

If you want to go the high moly route rather than esters, Havoline or Pennzoil is the way to go. But I can tell you from my experiments the esters do better, but either way the Auto-RX treatment first is a must.

 

[redtan819]

Yup, definitely doing the autorx thing. Sounds like many people have had good experiences with it.

Also read over the Chevy piston slap thread a while back, and it seems more people also agree that the castrol syntec oil works better than M1 which sounds the worst (which I have right now).

Guess I know what the next oil change in 1500 miles will be with.

 

[G-MAN]

Here's a vid clip of my 3.4. The main thing you hear is the rattle of the PCV valve but if you listen very closely you can hear some piston slap very faintly. Just turned 160,000 miles on this engine. Still doesn't use a drop of oil between changes and gets 28 mpg on the highway.

 

[Merkava_4]

For what it's worth, I've had very good results reducing piston slap in my little McLane edger. The Briggs & Stratton engine is very old and should probably be replaced, but it keeps on running very well with Castrol HD40.


Just so people know what I'm reffering to:

 

[redtan819]

That clip sounds great GMan, I could only dream to make my engine sound like that.

I think you've seen the clip that I posted earlier right? Did your motor sound anywhere close to that, or was urs much quieter in the beginning? Also, was you clip right at startup, or after it warmed up.

 

[redtan819]

Here it is again, yours sound a helluva lot better

http://www.youtube.com/watch?v=lPYkW25o-XQ

 

[G-MAN]

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That clip sounds great GMan, I could only dream to make my engine sound like that.

I think you've seen the clip that I posted earlier right? Did your motor sound anywhere close to that, or was urs much quieter in the beginning? Also, was you clip right at startup, or after it warmed up.

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The engine was warm in this clip, but not fully warmed up. I'd driven it about two miles to the pharmacy to pick up a prescription and I took the clip when I got back.

The only time mine ever sounded as bad as yours was the time the dealer gave me "complimentary" oil change and put Valvoline in. This was back when Valvoline was junk. I'd been using Mobil 1 TriSyn and the esters in that did a good job of keeping the engine quiet. I knew as soon as I started it up they had changed the oil just from the sound. The next morning's cold start was horribly loud. As soon as I put Mobil 1 back in the nose level went back down. Current Mobil 1 has very little if any esters in it so it doesn't do much to help the piston slap.

As good as the old TriSyn Mobil 1 was at dampening the noise, it wasn't as good as Castrol Syntec Blend or GTX Startup.

Let me caution you not to get your hopes up too much. Your engine may never be as quiet as mine is. But I'm confident that if you do the Auto-Rx treatment and use Syntec, Syntec Blend, or GTX Startup afterwards it will be significantly better.

 

[redtan819]

Yeah, ur engine sounds dead quiet, or at least it does so watching the clip.

So yeah, I can't expect it to become like that, but anything, even just a little dampening will help. I just need to ride out this car for another year or so (graduating college and saving up for a GTO), so any little bit will help.

 

[redtan819]

Oh yeah, another thing, I read that GTX startup is no more, so then I should just use the regular castrol, or should I go with the syntec after the 1500 mile treatment?

 

[G-MAN]

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Oh yeah, another thing, I read that GTX startup is no more, so then I should just use the regular castrol, or should I go with the syntec after the 1500 mile treatment?

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Use GTX for the Auto-RX treatment and rinse, then use Syntec Blend or Syntec afterwards if you can't find GTX Startup.

GTX Startup is sill available at my local Advance Auto stores.

 

[redtan819]

Cool thanks. I just recently changed mine to M1 dino less than 300 miles ago, so I think I'll just stick with that for the treatment stage. If it doesn't do much, the next change will be with gtx and another shot of autorx. Their site recommends 2 treatments anyway, so I'm sure it will be fine with the M1 I have in right now.

 

[G-MAN]

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Cool thanks. I just recently changed mine to M1 dino less than 300 miles ago, so I think I'll just stick with that for the treatment stage. If it doesn't do much, the next change will be with gtx and another shot of autorx. Their site recommends 2 treatments anyway, so I'm sure it will be fine with the M1 I have in right now.

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M1 dino? If you've got Mobil 1 in there I wouldn't use that for the Auto-RX treatment or rinse. If you've got Mobil 5000 in there, that should be okay.

 

[Curious Kid]

Since there was mention of such noise on a piece of garden equipment, I bought myself a 7hp sears tiller this spring, and when I have the thing idling to warm-up, it seems to knock away like redtans's engine. I guess I can now say I'm gaining some experience with it.

When I throttle up slightly, I'm able to reduce the noise, and it goes away at full throttle - which still has me pondering if it has something to due with lube supply?? Runs great otherwise and nothing noticeable in the oil, though I'll get a better look when I change out the initial fill soon. I just might try some of my remaining GC, though I have started to use HDEO's in the rest of my equipment (5w/15w-40).

Oh yeah, the engine still "knocks" when I throttle down to the factory setting after use, which might seem a bit low for a single cylinder (just under 200cc's I believe).


On another note - when I rebuilt a 1.6L 4 to a '77 chevette which was rebored due to cylinder ridges, I had noticed that a slight knocking developed towards the cylinder's in the block (the old broomstick to ear method). I later pulled the crank to be machined this time and be given sized bearings - the original's only had some 15k miles over 17yrs, and to my eye at the time, looked good ( I still have them in storage as a matter of fact). Upon reassembly and running, the sound was still there. I thought that though I had indexed the connecting rods, that I had somehow done so as to enable mis-orientation, and thus throwing off the alignment which thus caused the knocking upon ignition pressures. I can't recall endplay measurements as it's been sometime...that is if I even took them (First rebuild while I would walk/bike to work and for parts at times...).

Needless to say, the more I'm thinking it was piston slap - or dare I say I'm beginning to wish it was instead of a bad rebuild. I guess I'll never really know as I sold the car a few years later as the tranny was starting to slip from 1st-2nd (TH200). The engine though still knocking under 1.5-2k was still running well (some cold carb issues which I now believe would have been solved by increasing the accelerator pump's discharge), and holding oil pressure. I've learned a lot from that $1, yellow bee, Grandmother's special!

Take care and good luck.

 

[Ken2]

The simple answer is that multigrade oils pass a cold viscosity test as well as a hot viscosity test, and single grade oils have no such cold test.

The real answer is that multigrade oils are the most modern, best formulations. Single grade oils are not formulated to the newest standards. Use a multigrade oil. Try a CJ-4 15W-40 oil. In winter use a lighter viscosity in your Mass. climate