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Cummins N14 5W40 vs 15W40 #4754096
05/11/18 10:58 AM
05/11/18 10:58 AM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
I have a 1999 Monaco Signature 45í Class A. The motor is a Cummins N14. Just added a FS2500 bypass filter plus the factory Fleetguard FF filter. I havenít filled it with oil yet, but want to run synthetic and do EOC. Any issues with running 5W40?

Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754105
05/11/18 11:08 AM
05/11/18 11:08 AM
Joined: Oct 2004
Posts: 3,128
Midwest, Illinois
beanoil Offline
beanoil  Offline
Joined: Oct 2004
Posts: 3,128
Midwest, Illinois
Probably not, but in Arizona, no need to. The 15w40 would be just fine.
There is no advantage to synthetic unless the conditions call for it. Temperatures or extended drains, maybe, but there are many, many UOA that prove that a conventional will do just as well as a full synthetic, depending on application.


beanoil: Tough under heat, real dirty afterwards.
Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754121
05/11/18 11:21 AM
05/11/18 11:21 AM
Joined: Oct 2010
Posts: 7,043
Michigan
A_Harman Offline
A_Harman  Offline
Joined: Oct 2010
Posts: 7,043
Michigan
Just run 15w40. Valvoline Premium Blue Classic if it's still available. Or Mobil Delvac MX.


1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck
Re: Cummins N14 5W40 vs 15W40 [Re: A_Harman] #4754128
05/11/18 11:29 AM
05/11/18 11:29 AM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
Neither of those are available in my town. My only synthetic option is the Rotella T6 5W-40

Re: Cummins N14 5W40 vs 15W40 [Re: A_Harman] #4754129
05/11/18 11:32 AM
05/11/18 11:32 AM
Joined: Feb 2009
Posts: 1,583
wv
krismoriah72 Offline
krismoriah72  Offline
Joined: Feb 2009
Posts: 1,583
wv
Many millions of miles logged on the old N14 engines using nothing but conventional 15w40. Spend the money on clean air filters and clean fuel filters as well as coolant.

How much of an extended drain do you want? 10000 miles is the normal change interval.

Re: Cummins N14 5W40 vs 15W40 [Re: krismoriah72] #4754149
05/11/18 12:01 PM
05/11/18 12:01 PM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
My plan was to go as long as possible using analysis. I figure with the bypass filter I should be able to easily go 20,000 miles. That was based on my reading regarding synthetics since they have a higher TBN

Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754172
05/11/18 12:18 PM
05/11/18 12:18 PM
Joined: Feb 2009
Posts: 1,583
wv
krismoriah72 Offline
krismoriah72  Offline
Joined: Feb 2009
Posts: 1,583
wv
Originally Posted By: offtosleep
My plan was to go as long as possible using analysis. I figure with the bypass filter I should be able to easily go 20,000 miles. That was based on my reading regarding synthetics since they have a higher TBN


Rotella T4 15w40 TBN is 10.27 http://pqiadata.org/Shell_Rotella_T4_15W40_4192017.html

Delvac 15w40 TBN is 11.0 http://www.pqiamerica.com/June%202014/ExmoDelvac13001540.htm


Rotella T6 5w40 TBN is 10.94 http://www.pqiamerica.com/June%202014/shellrotellat6.htm

Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754185
05/11/18 12:41 PM
05/11/18 12:41 PM
Joined: Oct 2012
Posts: 1,224
Rabbit Creek, Alaska
jayg Offline
jayg  Offline
Joined: Oct 2012
Posts: 1,224
Rabbit Creek, Alaska
Higher starting TBN doesn't necessarily mean it lasts longer though. TBN can drop faster or slower depending on oil and conditions.


If your only synthetic option is T6 in 5w40 then run it if you are dead set on extended drains. You don't need it for the winter weather starting obviously but I would feel more comfortable with the synthetic going 20k miles with the bypass filter setup.


2017 Ram 1500 Ecodiesel- CP Triton ECT 5w40
2015 Prius C Napa 0w20
1973 240Z 10w30 VWC from '73
1973 Triumph Bonneville 750 M1 5w50
1967 BSA 441 Victor Special M1 5w50




Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754194
05/11/18 12:55 PM
05/11/18 12:55 PM
Joined: May 2010
Posts: 1,094
Ocala, Florida
racin4ds Offline
racin4ds  Offline
Joined: May 2010
Posts: 1,094
Ocala, Florida
If you're attempting extended drain intervals then yes you should use synthetic, and you should being that you've went to the expense and trouble to install a bypass filter setup.How many gallons of oil does the N14 hold?

I'm sure that ol Cummins will love the Rotella 5W40 either way.


Just say NO to thin oils and M1!
05 F350 Powerstroke
05 Hyundai Tucson
08 Legacy GT
Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754195
05/11/18 12:59 PM
05/11/18 12:59 PM
Joined: Jun 2003
Posts: 17,506
Deplorable in apple valley, ca
Chris142 Offline
Chris142  Offline
Joined: Jun 2003
Posts: 17,506
Deplorable in apple valley, ca
Exactly how many miles are you thinking of running the oil? Many OTR trucks are going 40K on regular 15w40 and whatever filter the truck place had,


02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754276
05/11/18 02:27 PM
05/11/18 02:27 PM
Joined: Oct 2014
Posts: 12,053
Idaho
CT8 Offline
CT8  Offline
Joined: Oct 2014
Posts: 12,053
Idaho
The only advantage the 5w- will buy you is below freezing starts. If you can use the starting advantage then run the syn.


2015 Ford F150 2.7
2018 Ford F350 6.2
Re: Cummins N14 5W40 vs 15W40 [Re: racin4ds] #4754345
05/11/18 04:05 PM
05/11/18 04:05 PM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
I canít find anyone who has run the 5W40 in that engine, hence my concerns. The manual calls for 14 gallons.

Re: Cummins N14 5W40 vs 15W40 [Re: CT8] #4754347
05/11/18 04:06 PM
05/11/18 04:06 PM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
Despite being in Arizona, I donít live at the lower elevations. We were freezing up until about a week ago. I live at 8000 FT ASL

Re: Cummins N14 5W40 vs 15W40 [Re: Chris142] #4754350
05/11/18 04:09 PM
05/11/18 04:09 PM
Joined: Jul 2016
Posts: 6
Arizona
offtosleep Offline OP
offtosleep  Offline OP
Joined: Jul 2016
Posts: 6
Arizona
Iíd love to go that long! I think with UOA and the bypass filter, Iím hopeful. I hate wasting good oil just because itís been. Year. I donít think Iíll put more than 20k per year anyway. Mostly just hate wasting 14 gallons of oil when I donít need to

Re: Cummins N14 5W40 vs 15W40 [Re: offtosleep] #4754443
05/11/18 06:48 PM
05/11/18 06:48 PM
Joined: Dec 2013
Posts: 2,303
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,303
Fort Worth, Texas
Originally Posted By: offtosleep
I canít find anyone who has run the 5W40 in that engine, hence my concerns. The manual calls for 14 gallons.


A lot of people have ran 5w40 HDEO in their N-14's, 350 engine hours should be easy to do with just about any good quality HDEO......That's a lot of run time for a recreational vehicle!!


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
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