Switching to Synthetic 5W-40

[jschildm]

I have been running AMSOIL 15W-40, but am contemplating switching the the 5-W40 after seeing some threads about people have better cold starts and idleing.

I was curious if anyone has used this particular oil, or sees an issue with switching from a 15W-40 to 5W-40? The truck has just under 160K on the clock, and i have been running the 15W-40 full synthetic for about 15K or a bit more.

Thanks in advance for the thoughts.

 

[amarillo250]

5w40 Valvoline Extreme blue all year long and makes a big difference in cold weather

 

[JCart]

Mobil 1 full synthetic 5-40w year round with a Donaldson Endurance ELF 7405 oil filter. In addition I run a Luber-Finer Zgard 9750 by pass filter. Never ran used oil analysis though... but seems to fire right up in cold weather.

jrc

 

[Buffalo444]

Running that exact oil in my rusty behemoth. Starts great in every temp so far, been as low as 8* and starts and runs like its 90* out.

sent by the beard

 

[lincolnlocker]

with it being amsoil you might not notice much... when i first got my truck i tried a couple different synthetics and the 15/40 amsoil started better then the other brands of 5/40... it will only help but i dont know if its worth switching unless they are the same price, why not. ive never had a problem with my truck starting with delo or premium blue 15-40 even in the -20s in minnesota winter while working out there.

live life full throttle

 

[jschildm]

My truck starts ok, but I figure it can't hurt. I am not too worried about it, but did anyone notice fuel mileage differences? I think I am going to take a sample this time and send it in for analysis, and then do the same after some 5w-40. Price isn't much different.

 

[jbkingranch]

Switch from 15w-40 Amsoil to 5w-40 a little over a year ago when I moved from Texas to North Dakota. I cranked it up last weekend with my EOT 3 degrees and ECT 2 degrees. Smoked a little at start up but cleared up in about 30 seconds and ran good. Did my first oil change at 15,000 miles this summer. Got a oil report back through Oil Analyzers Inc. saying I had 3.6% fuel dilution. Other then that the viscosity was still good with the fuel dilution, soot was still <.1% with the 2 micron bypass oil filter.

I have about 5500 miles on my current oil. Did a sample at 5100 miles through Butler Machinery's lab (the Cat dealer I work for) and it came back with no fuel dilution. Talked to some guy about the fuel dilution problem just going away and they said it caused from all the hard cold starts from last winter. Anyway I still haven't sent in a sample of unused oil to get a base line yet but will be very soon. After I get that info I'll be able to post up some comparison data for you.

 

[Campspringsjohn]

I doubt that you will see much difference switching. Amsoil makes specific oil for specific applications. What they recommend for newer trucks may not be the best to run in our older trucks. They have a good staff on hand, and it might be a good idea to ask them which they would recommend for your particular application. Obviously where you live, and how you use your truck are factors that need to be considered.