What Weight Oil?

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Nov 7, 2002
I have two older autos - '92 Escort and 94 Mazda B-4000, both with over 100,000 miles on the clock. I usually run 10 W 30, but a friend gave me a case of 10 W 50 oil. I live in central Alabama which has mild winters. Is there any significant reason that I shouldn't use the 10 W 50 in either of my vehicles? [Roll Eyes]
two words: owner's manual (if it's OK by the books you should be OK) I assume the oil to be synthetic because a 40 point spread just isn't so doable with a dino oil (Why didn't you post the brand?) I wouldn't know why you should need a 10W-50. All that said it may not harm the cars......
Well, back in the early 80s I ran Castrol GTX 10W50 exclusively in my VW Rabbit and that was in CT where winters were a little tough. Had 115,000 when I sold it but it seemed to do fine on that dino 10W50
Hola Pablo. I didn't say I felt I needed to use the 10-w-50 (Castrol GTX non-syn). I was given a case and I just wanted to know if there was any reason not to use it. Could it creat damage to my engines? Warranty is not an issue here. Is this something I should hold off till summer and hot weather?
Tell us more about this 10w50, is it oil that has been sitting around for 10 years and may be well out of date? If it's not SL formula oil I wouldn't take a chance. Personally I think it'll be way too thick for those cars, not to mention the fact that it'll contain a ton of VII in it.
thiggy (thigster? [Smile] just kidding - like the name! ) I don't like that oil. I wouldn't use a dino 10W-50 in my lawnmower (hey I have a Honda)... The viscosity index improvers just aren't lubricants.... And as patman points out, if it's old, then for sure don't use it.
Another thing to consider is that the your gas mileage will suffer somewhat with the 10w-50. It may cost you more in gasoline than the oil is worth.
Originally posted by Greg Netzner: Not me, boy; I'd blend it with 20%-50% M1 0W-30 & run it at least 5k mi a pop! But then, I'm a cheap-a**-bas****!
[LOL!] I think I would do that too. Rick [ November 13, 2002, 08:44 PM: Message edited by: Last_Z ]
Not me, boy; I'd blend it with 20%-50% M1 0W-30 & run it at least 5k mi a pop! But then, I'm a cheap-a**-bas****! [ November 13, 2002, 06:21 PM: Message edited by: Greg Netzner ]
OK thiggy, I feel my previous reply was a little too flippant. The other comments about this dino oil having a ton of VIIs is right on, but that doesn't necessarily mean it should be tossed. Rethinking the "blend it" concept a little, I guess what I'd REALLY do in your situation is blend it somewhere between 40-60% with M1 10W-30 or 15W-50. I think we've all agreed that the new 10W-30 & 15W-50 are M1's least VII, most stable (non-thickening/non-thinning) oils. Let's assume that you can expect the GTX to thicken a bit & thin a lot. The advantage to the 10W-30 is that it starts at a syn's 10W (better flow than a dino's 5W) & won't ever drop below a 30 when hot. The advantage to the 15W-50 is that it flows better than a dino's 10W & has a boosted anti-wear pkg in it to offset whatever degradation has occured in the GTX. Disadvantages? Well, the 10W-30 doesn't have the advertised add'l A/W pkg, & using 15W-50 means it's gonna stay a lot heavier. I really don't think 50wt is a problem for your vehicles/area, but it's obviously not a necessity. (Remember, it's still a 10W when the engine's cold.) I think I'd go with 10W-30 for 5k mi. It really comes down to your comfort level. I don't think using the GTX will harm either vehicle, & blending it is really just "insurance" if you don't want to toss it. I'm very much pro-extended-drains, so if I got a case free I'd try to make it work for me as much as possible. Also, I wouldn't run it in my newer, still-in-warranty car, but I would in my older, 160k mi car. But are YOU comfortable with that? I guess I should now add "anal" to my previous self-description. [Roll Eyes]
To answer your questions....first off the 10-50 will be roughtly the same as the 10-30 (you've been using) with respect to start-up since, aft all, it is a 10...so you shouldn't have problems using it "in the winter". The difference in the 2 comes from the 50 which means the oil will be thicker at operating temperature. Will this matter? Probably not. You will have a thicker film thickness when hot. Shouldn't matter...the engine will run smoother, probably accelerate more gradually, economy may diminish ~1-2 mpg...but, definately safe to use...go for it.
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