Conventional 5W-30 No Longer Available?

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95burban

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I’ve always run 15-40 rotella. Everything from My 547 alky big block to my 2010 gmc and everything in between. I buy it in bulk. Whether it’s right or wrong I’ve never had any issues.
 

highwaystar

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Read that the "additives" in conventional oils that have a wide W spread (10w-40) etc. promote varnish/coke build up UNLIKE oils that have a tighter w (10w-30). Fact or Fiction?
 

Schurkey

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It would cost me more to have some lab tell me I can extend my oil changes than just doing the oil change.
Short-term, yes. Long-term, no.

Interesting. Is there any way to tell what API group a specific oil is? Or is it just safe to assume that all full synthetics are group 4 while all "synthetic blends" are group 3?
There's no easy way to tell. The last thing the oil companies want is to draw attention to the phony "synthetic" issue.

You might contact them and ask what group number it is.

Safest to assume you're being cheated. I bet EVERY "synthetic blend", and practically-all of the "full synthetic" oil sold is Group III. Very little is "real" synthetic.

Read that the "additives" in conventional oils that have a wide W spread (10w-40) etc. promote varnish/coke build up UNLIKE oils that have a tighter w (10w-30). Fact or Fiction?
GM quit suggesting 10W-40 decades ago. I could never get a straight answer "why", except that there were vague references to additive package, and "too much" additive was needed to get the wider viscosity range. The GM "Goodwrench" oils back in '83--'84 were not available in 10W-40.

I assumed that it was more of a "marketing" thing than an actual problem. But maybe I'm wrong.
 

PlayingWithTBI

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GM quit suggesting 10W-40 decades ago. I could never get a straight answer "why", except that there were vague references to additive package, and "too much" additive was needed to get the wider viscosity range. The GM "Goodwrench" oils back in '83--'84 were not available in 10W-40.

I assumed that it was more of a "marketing" thing than an actual problem. But maybe I'm wrong.
I'm guessing to meet CAFE (Corporate Average Fuel Economy) standards.
 

TagAllen

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I noticed this over a year ago managing an Oreilly. Actually got cussed out a couple of times by older guys over it. Had two different guys actually come back and appologize when they realized that it was no longer being made and that we offered what was being made. Oil technology has moved on and synthetic blend will not hurt a thing. If you have a flat tappet cam go with VR1 or equivalent, but that typically starts at 10w30. From memory, don't shoot me if I am off a little, but the only real difference in the viscosity glide between 5w30 and 10w30 starts around ~0°F. Once you are above near arctic temps the oils are for all practical purposes the same. Synthetics are more eco friendly and most new engines REQUIRE them. Conventional has gone the way of straight 40wt and the dodo bird. I break every roller cam engine I build in with synthetic.

My real worry is the day they stop making DexIII. The low viscosity Dex VI in our transmissions IMO is a death sentence and causes them to die an early death.
Where are you getting DexIII? Have not been able to get it in east central IL for years.
 

df2x4

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^ Yeah.

From what I understand several companies are still producing and selling Dexron 3 compatible fluid, it's just not officially licensed by GM any longer.

GM says to use Dexron 6 in it's place except in transfer cases or power steering systems that originally called for Dexron 3. For those transfer cases they recommend GM manual transmission and transfer case fluid, part number 88861800. For power steering systems, GM power steering fluid part number 9985010.
 

SAATR

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Use an Allison TES-389 approved fluid, if you need absolute confirmation that the additive package is good. It's an HD DexIII-H fluid, and has existed since GM did still certify DIII fluids.
 
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