Regarding Oil Viscosity

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Regarding Oil Viscosity

Postby Rich » Fri Nov 21, 2008 12:07 pm

Generally I hear to run 15-40 and always have. But I was reading my manual and it recommended 2 oils, 15-40 and 30w.

It gives a scale for each oil. Seems like they only recommend 30w for temps above zero degress and 15-40 for sub zero temps.

Living in CA I've never seen subzero temps. Ocassionally (rarely) we get in the high 20's.

So, I'm wondering if there is benefit to running 30W?

For the record I run Rotella 15-40 - my local auto parts store carries Rotella 30W.

The reason I ask is - My engine runs quieter and smoother when I first change the oil (about the first 500 miles). I can actually hear it quiet down about 5 seconds after I start it after changing the oil. I'm thinking 30 is thicker and may prolong that? Or not?
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Re: Regarding Oil Viscosity

Postby IH-2 » Fri Nov 21, 2008 1:25 pm

generally, straight-weight oils(30w) are more resistant to thermal breakdown than multi-weight oils(15w-40). There's some EPA guidelines for multi-weight oils in gas engines, but I'm not sure if they apply for diesels. In your climate i'd say run the 30w. just my .02
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Re: Regarding Oil Viscosity

Postby PhilD » Sun Nov 30, 2008 12:50 pm

Rich wrote:I'm thinking 30 is thicker and may prolong that? Or not?
Straight 30 is definitely thicker than 15W40 when cold, but not when warmed up. In simple terms when cold 15W40 is a 15W oil and when at operating temp it is a 40W oil. The W is for Winter, (not Weight), and as the name implies is predominantly to do with cold weather viscosity. In hotter climates this because less important.

That said, there is a lot more to choosing the right oil than just the weight. As I understand it the "cushioning" ability of 30W oil in diesel motors is not very good, and 15W40 is much better. I would personally run a good syn 15W40 in a diesel motor before 30W.
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Re: Regarding Oil Viscosity

Postby PhilD » Thu Oct 01, 2009 7:05 am

Rich wrote:I can actually hear it quiet down about 5 seconds after I start it after changing the oil.
I know a spammer brought this topic but up, but reading it again that sounds like your filter is draining, try a different brand of filter. On my JK Mobil1 and K&N filters both drain back resulting in a noisy start-up until the filter fills back up again.
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Re: Regarding Oil Viscosity

Postby hummech » Thu Oct 01, 2009 6:42 pm

in california, stick to the 15w/40 motor oil. that is what i have been using for years and was also recommened buy AM General to use in hummers in our area.
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Re: Regarding Oil Viscosity

Postby superluke » Fri Oct 02, 2009 12:26 am

Glad to hear about this. I just picked up 15W40 today. 8)



Is it correct that the oil capacity is 7 to 8 quarts? This is my first change and I bought 2 gallons.

Thanks.
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Re: Regarding Oil Viscosity

Postby Rich » Fri Oct 02, 2009 10:34 am

2 gallons is what I always use (with filter change). That really tops it off so be sure to give it time to all drain out. I'm not sure all H1's are the same though.
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Re: Regarding Oil Viscosity

Postby Rich » Fri Oct 02, 2009 10:50 am

PhilD wrote:
Rich wrote:I can actually hear it quiet down about 5 seconds after I start it after changing the oil.
I know a spammer brought this topic but up, but reading it again that sounds like your filter is draining, try a different brand of filter. On my JK Mobil1 and K&N filters both drain back resulting in a noisy start-up until the filter fills back up again.


The HML has a list of filers with anti-drainback filters. I only use those brands (they are actually required for the later H1 years). I think my tapping is actually a noisy injector. I've read that putting a quart of transmission fluid into the fuel will correct it most of the time but I can't seem to bring myself to pour tranny fluid into my fuel. :lol:
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Re: Regarding Oil Viscosity

Postby PhilD » Fri Oct 02, 2009 11:16 am

Rich wrote:I've read that putting a quart of transmission fluid into the fuel will correct it most of the time but I can't seem to bring myself to pour tranny fluid into my fuel. :lol:
Banana skins in the diff will also quieten down a noisy diff, but I wouldn't do it either :lol:

Used to be common practice to use ATF in diesel fuel, but from what I understand the friction modifiers in modern ATF can cause injection system problems.
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Re: Regarding Oil Viscosity

Postby hannamarin » Thu Aug 04, 2016 11:59 pm

thanks for your appropriate advice concerning all stff of the bicycle! http://bigessaywriter.com/blog/climate-changing-or-main-problem-of-the-21st-century will tell you about climat and what changes do we have in the 21 century!
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