My RV is a 2007 but built in 06 with a Cat C7 Wax 30227 engine. Does it require Ultra low sulfur No. 1 or can I still use No.2 diesel fuel
(You can tell, this is my first diesel RV)

If your engine requires ULSD fuel it will say this on the dash fuel guage.

ULSD is only required in ENGINES built after Jan 1, 2007. Since yours obviously has a 2006 engine, it does NOT require ULSD.

As GaryKD says, if it needs ULSD it will say so quite prominently.

Thanks guys. I am on a 3000 mile trip and have only filled up twice so far. Both times ULSD. But I understand I may get a little better mileage with the old type fuel. Is that true?

Probably not enough to notice. LSD, like leaded gas did, is becoming less and less available.

facts on diesel fuel This website contains all the information about ULSD (S15), and what diesel powered vehicles are required to use only ULSD. The original EPA regulatory announcementrequires all 2007 model year diesel powered vehicles use only ULSD diesel fuel. At the last moment, the EPA revised this requirement to allow vehicle manufacturers to use existing inventories of 2006 engines until Jan 1, 2007. This, to me, means if your vehicle if not equipted with a DPF (diesel particulate filter), you may use LSD (S500) fuel.
Mileage; the EPA forecast 1-2 less mpg using ULSD, and a 4.5-5 cent increase in price.

quote:

Mileage; the EPA forecast 1-2 less mpg using ULSD, and a 4.5-5 cent increase in price.

I really can't tell any difference in mileage from the different fuels. Of course I may be getting a little mileage now because of the 17,000 miles I have on engine. They're way off on fuel increase - I think it has increase about $2.00 a gallon since I purchased the coach.

I took a 4,800 mile trip in May and didn't see any difference in mileage. Most places I fueled at only had ULSD.
Tom

I have seen no difference in MPG because of using LSD or ULSD fuel.

Me either.