20w40 blend

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Jul 4, 2003
San Antonio, TX
I don't think there is a 15w40 blend. Which grades do I mix to get a 20w40 synthetic blend? Has to be Valvoline. Thanks, Joe
Have I got an oil for you! Go to your local NAPA parts store and they should have Valvoline Durablend 15w40 in stock. As far as I know it is the only passenger car motor oil in 15w40 and it's a synthetic blend. That's what is going in my crankcase for this summer. [Happy]
I'm not sure how you'd get the 20w number you looking for unless you find some 25w-40 Valvoline lying around the shelves somewhere to mix with a 15w-40. I don't think you're going to find any 25w... [Confused]
tallpaul - I'll check NAPA even though the closest one is 25 mi away. Never heard of 15w40 durablend. Hope they have it! I would use it year round, here. toynsat - haven't seen any 25w40 either. wow, that's 2 oils i haven't even heard about here. Thanks again, Joe
Originally posted by jorton: tallpaul - I'll check NAPA even though the closest one is 25 mi away. Never heard of 15w40 durablend. Hope they have it!
Give them a call. If they don't have it in stock they can order it. I found out about it at the Valvoline.com site.
According to the API engine oil classifications ( http://www.infineum.com/information/viscosity.html ) the "w" rated grades are based on cold temperature properties like cold cranking and cold pumping. They also have to meet a minimum low-sheer-rate viscosity at 100C. Guess what? both 15w and 20w have the same low-sheer-rate 100C viscosity requirement: 5.6 cSt. So, while they can be thicker and maybe the 20w is normally made thicker than the 15w, I think you are pretty safe using either one. Minimum high-sheer-rate viscosity at 150C is also the same for both of these: 3.7 cSt. Not so for a 10w40 which is 2.9 cSt minimum. [ April 07, 2004, 02:09 PM: Message edited by: TallPaul ]
I used the 15W-40 Durablend in my 1959 Alfa Romeo Giulietta, which called for a 20W-40. It was a great oil, the car felt better with that oil than any other I tried. This was about 8 years ago. I'm happy to hear that it's still available. Ed
If you can't get the 15w40 Durablend, here is another way to do it (if you don't want to go heavy duty motor oil). Get some 10w40 Durablend and mix in about 1/2 quart or so of straight 40. That will increase the base oil viscosity while compensating by spreading the viscosity index improvers thinner. End result could be somewhere in the 15w40 area. Fine for summer, but would not mess with it in winter. The NAPA straight 40 SL oil is only $1.39 a quart (is Valvoline Super HPO). I know it's an old thread, but I just couldn't resist posting about my latest mind warped idea [Freak] for how to mess with oil that the experts spent much time and money tweaking so we would not have to mess with it.
Thanks for the 40 weight mix idea. When I posted this topic last april my son had just received his new 1990 Nissan 300zx with 172,000 miles on it. Now that I know it doesn't need top-offs between oil changes 5000 miles later, we've decided on using starburst oil so scrap the 40 weight idea. I'm mixing 10w40 and sae30 in my Sentra though. it uses 1 qt every 600 miles. Joe
Got it, Joe. I just tried the mix. Filled up with Citgo 10w40 and it was not putting out the kind of oil pressure I was getting with Valvoline Durablend 15w40 or Maxlife 10w40, so I added some 40 wt. Have a whole quart of 40 wt in with 5 qts of the Citgo. Still not as good of oil pressure. And the weird thing is the Citgo is listed as higher viscosity than the Durablend or Maxlife. Maybe it is the Auto Rx treatment I am going through (Citgo began first rinse), or maybe it is that the Citgo came from the dollar type store for 50 cents a quart. [I dont know] But for me, it's back to Valvoline (after the Auto Rx as I still have 11 qts of the Citgo left).
25w40 oil is available at the various marine stores. I suppose 1/2 15w40 and 1/2 25w40 would get you the 20w40, but I'd just buy a good 15w40.
I found a new way to make 20w40. Get some 20w50 and some Valvoline 20w (yes, that's right, only a "w" number to it) and mix them together. Murrays around here sells the 20w. May be able to order at NAPA.
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