Synthetic motor oil viscosity

[LRutigliano]

I've been considering switching to a synthetic motor oil...



However, all the synthetics seem to be rated as 5W-40 instead of 15W-40 for the conventional oils.



Is the 5W-40 synthetic oil ok to use?



I tow a very non-aerodynamic & heavy (10k+) 5er with my truck 100% of the time.



The local BiMart has Delo400LE synthetic 5W-40 on sale for $17. 99/gal. The stuff I normally use is Valvoline Premium Blue 15W-40 and it costs $12. 99/gal at the local Schucks.



I change my oil once/year just before camping season with maybe 3000 miles on it.



Thanks,

Louis

 

[WStephens]

This is what is available from Amsoil.
Synthetic 5W-40 Premium Diesel Oil (DEOQT)
SAE 10W-40 Synthetic High Performance Motor Oil (AMOQT)
Series 3000 SAE 5W-30 Synthetic Heavy Duty Diesel Oil (HDDQT)

 

[RobertHiltz]

Louis, There is 15w-40 synthetic oil available in some brands. I think that if in doubt follow the owners manual recommendations. Look at Mobil's commercial oils.

 

[steved]

They are both a 40 weight viscosity at operating temperature... the "5w" and 15w" are a cold weather flow characteristic (not a weight).



A 5w40 should protect the same as a 15w40 at operating temperature, everything else being equal.

 

[2Rowdy]

I have 100,000 miles on my 6. 7 running Schaeffer's supreme 9000 5w-40.

 

[JCyrbok]

I have 100k on my truck running Amsoil Heavy Duty Diesel and Marine 15w40 full synthetic. It is a 12TBN oil and my last oil sample was at 35k miles on the current oil and still good for continued use. I do have a bypass filter which helps.



J-

 

[jakprince]

If you only run it 3000 miles a year whats the point of going to synthetic?

 

[RPlamondon]

Best in cold, heat, extreme conditions, quicker lube in start up, better lube in all conditions, longer life. I also use the Amsoil filter which is the best on on the market per a master mechanic friend.

 

[bheiting]

The manual for my '07 5. 9 calls for syn. 5w40 under all temp. conditions. Yours
should be the same. Cummins suggests dino oil for the first 10k for break in.

 

[LRutigliano]

The manual for my '07 5. 9 calls for syn. 5w40 under all temp. conditions. Yours

should be the same. Cummins suggests dino oil for the first 10k for break in.

The owners manual... :-laf Its been such a long time since I cracked it open... I looked at it tonight and saw what you posted.



Thanks!

 

[LRutigliano]

If you only run it 3000 miles a year whats the point of going to synthetic?

Because its 3000 miles of towing in hot weather up big grades at 18k to 19k GCW, with my non stock engine... So I want the most protection available.



Also, since it sits for the rest of the year, my thinking was that synthetic would hold up better for the whole year.

 

[LRutigliano]

I found Premium Blue Extreme at Napa tonight (the only place I could find that stocks it) for $24. 99/gal.



The $17. 99/gal for the Delo 400LE synthetic seems like a great deal.



I sure would like to try Amsoil (its what I run in the boat motor and outdrive), but I don't know how to purchase the stuff. When I bought it for the boat, they carried it at GI Joes (but they have gone out of business)...

 

[Breed]

I use Shell Rotella T synthetic for my CTD and I get it at Wally world for $20 a gallon with a filter from Genos. It has worked great for years here in Dayton, Nevada, I use AMSOIL in my Classic cars and tractor, Quadrunners and generator and really like the Oil and it lasts for a long time. Very happy with the synthetic Oils.

 

[DPalmquist]

I run Delo 400 Dino and 3qts of syn mixed. The best of both. . Seems fine w/97k.

 

[Crazy Horse]

I sure would like to try Amsoil (its what I run in the boat motor and outdrive), but I don't know how to purchase the stuff. When I bought it for the boat, they carried it at GI Joes (but they have gone out of business)...

Here's a link to buy Amsoil.



They can send direct to your house, in what ever quantity you want.

 

[BLNRAY]

360,891mi on mobil 1

 

[MVenditti]

I've been considering switching to a synthetic motor oil...



However, all the synthetics seem to be rated as 5W-40 instead of 15W-40 for the conventional oils.



Is the 5W-40 synthetic oil ok to use?



I tow a very non-aerodynamic & heavy (10k+) 5er with my truck 100% of the time.



The local BiMart has Delo400LE synthetic 5W-40 on sale for $17. 99/gal. The stuff I normally use is Valvoline Premium Blue 15W-40 and it costs $12. 99/gal at the local Schucks.



I change my oil once/year just before camping season with maybe 3000 miles on it.



Thanks,

Louis

Royal Purple has 15-40 rated for Cummins, Have it in mine. Can get it at Pep Boys and maybe Autozone or Check their site.

 

[LRutigliano]

Here's a link to buy Amsoil.



They can send direct to your house, in what ever quantity you want.

Thank you Crazy Horse! However, you just cost me approx $210 because I want to buy Amsoil I/O gear lube and engine oil for the boat and 12 qts of Severe Duty gear oil for the truck and Durango... :-laf



They have 3 different diesel engine oils... 5W-40 CJ, 15W-40 CJ and 15W-40 CI+ For my truck, I should get the 15W-40 CI+ right??

 

[d6c]

Delo 400 15w40le is way cheaper at Costco than the prices you quoted.

 

[LRutigliano]

Delo 400 15w40le is way cheaper at Costco than the prices you quoted.

I know, but I quoted DELO400LE 5W-40 synthetic...