Chilling Thoughts: AC usage - Dash versus Generator

[MN_Traveler]

Funny ... strange as it sounds, i did mot consider changing the oil myself (have not done it yet so did not consider that it is relatively straightforward). The thing that occurs to me is that i would guess most campgrounds would not appreciate your doing so on site. So ... where do you pull in and stop to execute that change?

[biggcrisp]

I would feel more comfortable changing the oil at a campground rather than a Walmart or rest area.

[okcnewbie]

Originally Posted by MN_Traveler

....Forget about cost or MPG ... it is a PAIN to have the oil change done on the road when you are trying to make miles. How best to defer or avoid that?

Don't use genny I suppose. The next best thing would be to get really good/efficient (like others here) at changing the genset oil. So, I don't think you're going to convince many that, " To use or not to use..... is the question".
With my Class C and only 1 passenger I never "need" the rooftop AC. With the shading the overhang provides and the vents directed to driver/passenger we are comfy.
When/if I get my DP the 150 hr oil change (as far as to use or not to use)will be so far down on my list of priorities that I don't think I'll ever consider it.
For you though; You should only consider MH's that have a genset with an easy oil change.

[Brob]

Originally Posted by MN_Traveler

Funny ... strange as it sounds, i did mot consider changing the oil myself (have not done it yet so did not consider that it is relatively straightforward). The thing that occurs to me is that i would guess most campgrounds would not appreciate your doing so on site. So ... where do you pull in and stop to execute that change?

On my particular coach I don't think anyone would even know what I was doing other than reaching into a basement storage area for something. Unless they're standing over my shoulder.

[keger]

Many many years ago when we own a TT we drove to Disney world for a week of fun and sun, about a 1000 mile trip. Just as we got into our camp site the Master cylinder went out on our tow van. We got a replacement at the local auto parts store. I replaced the unit in the camp ground and no one even came by to ask or see what I was doing. The replacement took me about an hour or so to change. So my guess is that changing oil and filter on your generator, assuming you don't make a mess will probably go sight unseen or at worse no one will care. Although you will always run into those nosey neighbors.

[Civdiv99]

Originally Posted by Brob

On my particular coach I don't think anyone would even know what I was doing other than reaching into a basement storage area for something. Unless they're standing over my shoulder.

That’s what I was thinking - it has all the impact to those around you as rearranging stuff in a basement compartment. Less, if stuff got loaded by grandkids and I gotta take stuff out first...

[MN_Traveler]

Originally Posted by Brob

On my particular coach I don't think anyone would even know what I was doing other than reaching into a basement storage area for something. Unless they're standing over my shoulder.

Well, my rig is a DP with the genset at the front of the coach. So ... instead of reaching in to a storage bin, the neighbors would see my legs sticking out the front of the coach. questions might ensue .

on the other hand - with this configuration, there IS the question on whether I want to get directly under a solid piece of metal bolted to the main frame of 30,000 odd pounds of rig without jack stands (which I do not carry). There have been MANY threads on the wisdom against doing that.

I did meet a gentleman last year that carried four 8x8 blocks, and used them (doubled up) under the axles as effective jack stands. I might consider starting to carry those.

[markgott]

How about the reverse of trying to heat the RV. Last January, driving through west Texas, the dash heat was useless. Will roof top units supply heat or do I use the Aquahot?

[Trackrig]

I can't say I notice a change to the milage on my DP running the A/C any more than some wind, hilly country or a lot of stop lights in small towns on the back roads.


Bill

[Journey39n]

I believe you have an RV with generator for your comfort, and generators are made to run thousands and thousands of hours. So if you need it for comfort, driving or camping, use the generator.

Changing its oil is a simple thing, just check your manuals to see about the proper interval. Most require the first oil change to be fewer hours than later. My first change was at 50 hours, after that, 250 hours. So check your model, and be mindful of your conditions.

I have my engine oil and generator oil plus all filters changed in the campground, with a local rv service that comes right to my site. I could do it all myself, but then have to mess with collecting and disposing of the old oil. I think 50 years of doing that is enough, I will let someone else to it now.

[Ret.LEO]

One way to save on Gen time or Dash AC............drive at night.

[Finance]

Originally Posted by MN_Traveler

Funny ... strange as it sounds, i did mot consider changing the oil myself (have not done it yet so did not consider that it is relatively straightforward). The thing that occurs to me is that i would guess most campgrounds would not appreciate your doing so on site. So ... where do you pull in and stop to execute that change?

State or federal CG where the rules don't prohibit maintenance is where I've done it. Pretty much every private CG has a rule against it.

[joemcmillen]

Originally Posted by MN_Traveler

There have been a number of threads in the last several years dealing with the question of using AC while driving - specifically dash AC versus roof-top while running the generator. It is clear from these discussions that 1) you CAN run the genny and rooftop generators while driving, 2) you get better gas mileage while using the genny instead of the dash AC, 3) this approach will work as long as you keep the coolant and oil in the genny at appropriate levels (and have fuel).

I have over the last several years done several cross-country "dashes" or longer trips, needing to rely on boondocking (Walmart or Flying J) while running the genny at night to power the AC. I have found on these trips that my real limit is the genny run time between oil changes (150 hours on my unit). Just looking at the numbers, it has been surprising how often I concluded that if I relied on just the genny and rooftop AC I would max out that 150 hour limit and need to find a place along the way to get the genny oil changed (a pain, and time delay I have sought to avoid).

My solution has been the following - which is a hybrid of what has been mentioned in the past: In the morning, it is usually cool enough that the dash AC can mostly handle things. I run it, directing it into the coach, turning up the fan and then directing it directly on to me as things heat up ... basically until I can not stand it. Then I shift to the genny and the roof AC units (usually 2 or so in the afternoon) to cool things. If I am making a very long run that day, later in the afternoon as the sun goes down I can shift back to dash AC. When I stop for the day, I run the genny and roof AC . It almost always seems that sometime in the night things cool off enough that I can turn off the genny (exception - eastern midwest and eastern south where things are often hot and humid). If you are driving on the high plains or at real altitude, things REALLY cool off - and the AC is surprisingly NOT needed at night (example, New Mexico or Wyoming - even in early august cools off to below 70 quite quickly!). In the morning it all starts over again:run the dash AC, etc.

Using this approach I may have sacrificed some gas mileage, but have been able to continue running for 6 weeks or more without needing to take the time to get that genny oil changed.

I invite thoughts, comments, etc.

Regards,
MMTraveler (currently in Atlanta, having come from New Mexico )

Hello, I am an infrequent responder to most posts, but yours hit home.

Look! your dash A/C requires between 8 and 12 hp. to run (very high, but true). That energy level is nominal in the grand scheme of pushing that behemoth down the road; so lets call the dash A/C a load nominal. Just run it!

Staying with the dash A/C, the compressor has to push refrigerant a long way (if you have a diesel pusher). That means that there are a lot of ways to loose refrigerant.

Check refrigerant pressure when you notice a loss of cooling! You probably have an r134a system and the gauge connections are in the front of the coach. This is an easy system to monitor. An r134a set of gauges is pretty cheap and will last around 10 years (seals). Add refrigerant if needed!

Run the gen-set only when you think that the coach is hot (you should have 2 roof/top A/C units).

So, getting to your real question: What about oil change intervals? your generator endures several different types of loads. If you are only running one A/C unit when running down the road, then it is only using a portion of its capacity; so it is running at part load. That means that the bearings are not being loaded to their capacity, which is how its rating is established. This means that you have the ability to adjust oil change intervals based on your discretion, which is a usage decision. Don't ever think that everything is predicated on specific rules. Change your generator oil when it meets your schedule!!!!! This is if you follow these rules: (use high quality oil (Mobil is my vote), use high quality oil filters, stay close to the OEM oil change rules.


My best 2-cents!


Regards,
Joe

[geordi]

Originally Posted by MN_Traveler

Well, my rig is a DP with the genset at the front of the coach. So ... instead of reaching in to a storage bin, the neighbors would see my legs sticking out the front of the coach. questions might ensue .

on the other hand - with this configuration, there IS the question on whether I want to get directly under a solid piece of metal bolted to the main frame of 30,000 odd pounds of rig without jack stands (which I do not carry). There have been MANY threads on the wisdom against doing that.

I did meet a gentleman last year that carried four 8x8 blocks, and used them (doubled up) under the axles as effective jack stands. I might consider starting to carry those.

Color me confused... Jack stands? Under a diesel pusher?

I have a rolling creeper in one of my bays, and what amounts to a service truck worth of tools usually with me. I can roll around under the coach on the creeper and STILL have nearly enough room to just about sit up under the coach - especially if the leveling jacks are extended enough to take the suspension weight off the tires. Even if I don't put the jacks down at all, there is plenty of room to roll under the front to change generator oil.

Now for making the job SILLY EASY - Prep yourself before you do this the next time. Go to Home Depot or Lowes and get the following parts (in brass) from the plumbing section. This is for most ONAN, but should work for Generac too if the drain points straight down. Modify as needed.

1/2" full-port ball valve, threaded. (non full port is OK, b/c the hole is still usually about the same as the drain port)
1/2" MPT to 3/8" barb nipple - This will be the actual drain port now, you can add tubing if you want to make it super clean into your container.
1/2" MPT to 3/8" FPT threaded bushing
3/8" x 1.5 pipe nipple.
On the chance that your plug is smaller (mine was) also get these:
1/2" MPT to 1/4" FPT threaded bushing
1/4" x 1.5 pipe nipple

Once you have the job done, you can return the nipple and bushing that you didn't need.
Use teflon tape (preferably the yellow gas-rated b/c that is also fuel rated) on the threads and assemble it so the handle points DOWN when the ball is open. Don't overtighten the connections, especially into the generator. BUT this is a permanent upgrade. There should be a frame member forward of the drain plug that would provide plenty of safety protection for this, and the front end should have about 2 feet of clearance anyway when driving. Anything larger than that goes under the front and you have other issues!

Your oil change is now just a 5 minute job. I haven't designed a remote oil filter mount for mine yet - already built a remote fuel filter mount and I'm using the Luber-Finer filters (same ones as for the engine) that can be gotten at any Pilot or Loves. I don't need to bathe in diesel and faff around with a flare connection anymore for maintenance, and that LF filter is $14, the Cummins filter was $35!
As an added benefit - I can change the fuel filter just by opening the front door, and the LF is easily 5 times the surface area of the factory one so it can be WAY more efficient at filtering.

FYI: The last time I changed my generator oil it had 500 hours on it. Oops. BUT - I run the generator pretty much 24/7 when I'm working on the RV and it is under load (A/C) with fully-synthetic oils. What came out was black (expected) but super clean. I'm going to get an analysis on this batch and see whether I might have even had more time on it.

The generator has about 2300 hours on it right now and is just so smooth and quiet when running.