going from 5w-30 mobil to 15w-50 or delvac 1300

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Nov 21, 2003
lake city sc
First off I would like to say what a wealth of information this site is! [HAIL 2 U!] I've been digging changing my own oil since I was 14. It's good to know that there are others out there with my addiction. [Big Grin] I have a 97 GMC Z71 with the 350 engine. I've always run syn. oil since I got it with 31000 miles on it. Now it has 80000 and I was thinking about going to a heavier oil ( 15w50 mobil 1 or 15w-40 delvac 1300). I've been going maybe 5500 to 6000 miles on each change. I was worried about the shearing of the mobil 1 but at the same time had thoughts about the non-syn delvac holding up. Any ideas from the "Lords of Lube" out there? o yeah, I use puroilator filters by the way.
I'm sure that Delvac 1300 wold be a good choice in SC. You could also mix up a batch of 10W-30 and 15W-50 Mobil 1, or of course the best choice might be the Delvac 1 (5W-40)
Why are you wanting to use a thicker oil? Is your truck using oil? IMHO a 50 weight is too thick for just a daily driver. 15w40 might be a good weight though. There have been a couple of very good UOA's posted on that engine. Check out the recent Valvoline synpower UOA posted on the 96, and check out my RP UOA on my 98. [Smile]
no, I'm not using oil any, just thought maybe a thicker oil would help my pressure stay up a little more ( start up is ~60 psi, hot driving 40, idle at red light 25~psi). i also read that some people had an increase in mpg with the thicker oils and seeing that I drive about 50 miles a day round trip to work I was looking at that option.
steeltoe, For 5k-6k mi intervals, I'd think D1300S should hold up perfectly well (& possibly be a better application for your climate). However, going from M1 5W-30 to M1 15W-50 or D1300S 15W-40, I wouldn't expect to see any mileage benefits. I think most of the reported increases have been with many of the full syn 40wts, & your two choices will be just a little too heavy to see much change. For that vehicle, in that climate, with those intervals, I'd change to D1300S for comparable protection at less cost.
First M1 15W50 is probably the best product that Mobil markets in a retail setting!! It is a thin 50wt. I have used it for years in daily drivers. SO far everyone that has tried it has had good results includeing a couple of Saturn owners. I think that you would be fine with 15W50. I do not know what your winters are like in NC so exercise common sense with viscosity apropreiate(sp) for temps. If money is not a factor and your vechile does not burn or leak a lot of oil I would stay synthetic. Delvac is a good oil but 1300 is not synthetic!
It only drops down to around ~20degrees F in the winter and that's only for maybe 2 or 3 nights. The only resources I have for oil are wally world, Advance, and Auto zone. So my opions are limited. The delvac is about $5.50/gal vs. $4.74 quart for the mobil. But at the same time I don't want to scrimp at the quality of the oil too much. Also, I've seen a lot of talk about German Castrol. How can you tell the difference between it and regular Castrol in the store? Thanks for all the input guys, it is greatly appreciated!! [bowdown]
If you have those choices in suppliers, and really want to try a heavier oil, how about Rotella T 5W-40? It's $12.88 a gallon at Walmart. I still don't know why you'd want to go away from what's been working for you though. The German Castrol 0W-30 is easy to spot at Autozone. Look for bottles with the 0W-30 printed on a red background on the front instead of the normal yellow one, and look for Made in Germany on the back... [ November 29, 2003, 12:22 PM: Message edited by: jsharp ]
It was just a thought to go to the heavier oil. I was just getting opinions from some pros on this subject. If nobody thinks it makes a difference though, I'll stick to the 30wt. Thanks alot for the advice.
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