SAE 30 vs. 20W-50 for a short OCI

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bunnspecial

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I need to do a quicky oil change in the MG. I'll be doing some engine work in September, so will be draining again then and consequently want to put the cheapest stuff that will actually be safe in there.

With temperatures as hot as they are now, and as hot as they usually stay through September in Kentucky, I'm thinking about dumping in SAE 30 or SAE40 rather than the normal 20W-50.

Any thoughts on doing that? Of course, I can just toss Supertech 20W-50 in it, but if a straight weight will give me as good if not better protection in 80º+ ambient temperatures, I'll do it.
 
If the car normally wants 20W-50, I can't imagine it'd do better on SAE 30 or SAE 40.

Is 20W-50 what the car calls for?
 
Originally Posted By: d00df00d
If the car normally wants 20W-50, I can't imagine it'd do better on SAE 30 or SAE 40.

Is 20W-50 what the car calls for?


Yes, 20W-50 is the specified grade, with SAE 30 listed as an alternate.
 
Originally Posted By: bunnspecial
Originally Posted By: d00df00d
If the car normally wants 20W-50, I can't imagine it'd do better on SAE 30 or SAE 40.

Is 20W-50 what the car calls for?


Yes, 20W-50 is the specified grade, with SAE 30 listed as an alternate.

Ah, alright. In that case, I'm inclined to think it'd be okay to run SAE 30 or SAE 40 if you want, and just take it easy on hot days until you can change the oil again.
 
Either would be a great choice. If I had to choose I would use the SAE 30 or 40.

Why? Any monograde would have less modifiers than any multi grade. More "pure" in a manner of speaking, and thats benefical if the modifiers are not needed.
 
Per Doug Hillary, the 20W50 was developed for the shared gearboxes in the Mini and later derivatives, resisting the shear that these experienced, not necessarily because the engine proper needed 20W50.

It then became the "standard".

SAE30 would be fine, as long as it's a decent additive package (i.e. not any of those on the PQIA website) HTHS over 3.5 is sufficiently ample.
 
Many 'B' owners run with one of the big three 15w-40's.

North American cars did come with an oil cooler as OE.

How is your oil pressure?
 
No major city in Australia is hotter than Houston Texas. The hottest city in Australia is Darwin, where it is almost 90 degrees year round but rarely hits 100 degrees. Sydney rarely gets above 90 degrees. I guess consistently hot is one way of measuring hot weather, and maximum temperature is another. source : Weatherspark.com

You want hot? It’s 112 F in Phoenix tommorow.
banana2.gif
 
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Originally Posted By: expat
North American cars did come with an oil cooler as OE.


The MGB had an oil cooler in New Zealand too...the B Series engine in the rest of the BMC range didn't. The MGB is hardly more stressed out in normal use than a Morris Oxford.
 
Originally Posted By: Shannow
Per Doug Hillary, the 20W50 was developed for the shared gearboxes in the Mini and later derivatives, resisting the shear that these experienced, not necessarily because the engine proper needed 20W50.

It then became the "standard".

SAE30 would be fine, as long as it's a decent additive package (i.e. not any of those on the PQIA website) HTHS over 3.5 is sufficiently ample.


Nowadays 20w50 (as I was told cca 3weeks ago in another thread) are pretty weak sauces compared to 70's - 90's 20w50...

So what do you suggest? API SG (of "that" era) had peak ZDDP levels...but is "castrated" nowadays...

API SL?

My pick (because of the shared sump) would be any full saps Rimula/Rotella HDEO (JASO MA) or any Tractor STOU oil with GL4 rating...

20w50 or no 20w50...well I am not a Yenkee and therefore I am not burdensome about/with an proper oil weight
smile.gif
If it shifts ok with 10w40 or 10w30...I will use that...
 
Originally Posted By: Snagglefoot
No major city in Australia is hotter than Houston Texas. The hottest city in Australia is Darwin, where it is almost 90 degrees year round but rarely hits 100 degrees. Sydney rarely gets above 90 degrees. I guess consistently hot is one way of measuring hot weather, and maximum temperature is another. source : Weatherspark.com

You want hot? It’s 112 F in Phoenix tommorow.
banana2.gif



I've said this many many times on BITOG and just gave up. It's about as bad as the claim that 0w30 in a snow blower at 30*F is noticeably easier to pull start...

"I use *insert stout non-available to US oil here*_________ because of the heat." No, you use it because there's no CAFE laws and as a result, the oils sold there don't have to be energy conserving. Look at the owners manual for a car in the US and compare it to the owners manual for the same engine in Australia.

That said, if the climate allows for it, there's no reason not to run a thicker oil IMO, but the "heat" certainly isn't the correct reason. HDEO giving one the warm fuzzies would be more of a correct answer.
laugh.gif
 
Last edited:
Originally Posted By: bunnspecial
I need to do a quicky oil change in the MG. I'll be doing some engine work in September, so will be draining again then and consequently want to put the cheapest stuff that will actually be safe in there.

With temperatures as hot as they are now, and as hot as they usually stay through September in Kentucky, I'm thinking about dumping in SAE 30 or SAE40 rather than the normal 20W-50.

Any thoughts on doing that? Of course, I can just toss Supertech 20W-50 in it, but if a straight weight will give me as good if not better protection in 80º+ ambient temperatures, I'll do it.


If indeed this has a shared sump thing, I take back what I said above in this situation.

Does the manual give a range of viscositys that can be used in certain temps?
 
No it's not a shared sump.

I mentioned that as that's Doug Hillary's point as to why the grade came to being and became viral in the English speaking world. (as opposed to those who speak American, LOL (and joking))
 
Originally Posted By: Shannow
No it's not a shared sump.

I mentioned that as that's Doug Hillary's point as to why the grade came to being and became viral in the English speaking world. (as opposed to those who speak American, LOL (and joking))


Oh no he di-int!!!
;^)
 
Originally Posted By: Silk
I wouldn't call an A3/B4 20W-50 weak in any way...but may not be on the shelf in the US.

Nope, not too likely. I know I haven't seen one here, either.
 
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