10w30 vs 5w30

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10w30 vs 5w30 when towing in hot weather 95/100F , oil will be changed after 5000 to 6000 mile 6 week trip.oil is quaker state UD.truck is an 09, 6L 1500 silverado.trailer is approx. 6800#.
 
5w30 & 10w30 are the same
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Both great oils, but the 10-30 is a slightly better fit for this application. There will be no benefit with the "5" in hot summer towing. 10-30 is slightly better here.
 
I doubt anyone can give you an answer that amounts to anything more than speculation, since there's really no information available regarding the specs of QSUD 10W30. OTOH, there is some information on the 5W30, both Amsoil's tests and PQIA test on 5W30 synthetics: link

The QSUD looked really good in that test, so I'd go with it since it's a known quantity. Lots of the speculation you hear about higher HTHS and lower NOACK in the 10W30 versions of oil often doesn't actually hold true when you look at the specs. Often times, it's just a more cheaply-made product.
 
Originally Posted By: gfh77665
Both great oils, but the 10-30 is a slightly better fit for this application. There will be no benefit with the "5" in hot summer towing. 10-30 is slightly better here.


I disagree with this blanket statement but QSUD 5w30 (as most SOPUS "syns" are thin 30grade). You may benefit from the slightly thicker 10w30QSUD.

Personally I would use a thicker 5w30 like M1 or Syntec(Edge). You will have a higher VI and the same if not lower NOACK. 10w30 "syn" is obsolete and pointless IMO. If I was that worried I would just use HDEO 10w30.
 
First number is lubricity (how well an oil flows) when cold. Second number is lubricity when hot.

So the only difference between a 10W-30 and 5W-30 is at startup, and in cold weather...

Both are 30 weight oils when hot...
 
Originally Posted By: mattwithcats
First number is lubricity (how well an oil flows) when cold. Second number is lubricity when hot.

So the only difference between a 10W-30 and 5W-30 is at startup, and in cold weather...

Both are 30 weight oils when hot...

It's far more complicated than that. It's my understanding that a 5W-30 RC motor oil would likely provide better highway fuel economy than 10W-30.

The first number has mostly to do with cold weather flow, and the standard is actually at different temps. The second number has to do with viscosity at 100 °C. What the viscosity is at any given temperate starting temperature varies greatly by the oil. Apparently some 0W-30 oils are thicker at 25 °C than most 5W-30/10W-30 oils.

http://www.widman.biz/English/Tables/J300.html

It should be possible to formulate a 5W-30 that's thicker than another 10W-30 at a typical warm-weather temperature. That's not typical, but possible.
 
Originally Posted By: y_p_w
It should be possible to formulate a 5W-30 that's thicker than another 10W-30 at a typical warm-weather temperature. That's not typical, but possible.

That's absolutely true, and even 0w-30s can be thicker.

@larryn: If you're out of warranty or don't care or it's allowed in the manual, go ahead and use 10w-30. Personally, I'd use the 5w-30 in it year round, towing or not.
 
Out of vogue here no doubt but 10w30 is still useful and will usually work very well in about anything you care to use it in. Heavy towing, summer, exactly a situation where 10w30 would be useful or even a better choice.
 
Originally Posted By: KCJeep
Out of vogue here no doubt but 10w30 is still useful and will usually work very well in about anything you care to use it in. Heavy towing, summer, exactly a situation where 10w30 would be useful or even a better choice.

Years ago I was looking to get a new car and found myself in an Acura dealer. I asked if I could look under the engine bay of an NSX and then popped it and tried to figure out how to get it up. One up, there was the typical info for recommended oils, spark plugs, etc on the air filter housing. I was a bit surprised that the recommended oil was a 10W-30 when 5W-30 was pretty standard by that time.

However, what's really out of vogue these days is 30 wt oil except maybe for lawn mowers. I remember hearing someone comment that for ideal protection (but not necessarily fuel economy), 30 wt could probably work better if there weren't concerns about cold starts. If it's summer temps, it should flow pretty quickly, and if you could ensure that it only gets warm starts or that a block heater is used long enough before starting, it would be ideal.
 
There is no significant difference in the two weights when your engine is warm. The 5W or 10W designate the “winter” weight of the oil. It relates to the flow-ability of the oil at low temperatures or at start-up; with the 5W having better flow characteristics at lower temperatures. The second number, “30”, gives the operating viscosity at 100C; when your engine is hot. Additionally, be aware that GM recommends that you use the 5W-30 for optimum performance and gas economy. Hope this helps, larryn! – The Pennzoil Team
 
Ssshhhh! Don't tell anyone, but I am running (almost free) straight 40wt. PYB in my Chevy truck this summer. MPG's, starting ease, oil pressure, RPM's, everything still the same. Remember...Quiet please!
 
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