15w40 vs 5w40 when TOWING

In a couple weeks I'm headed out east with the family. We will be towing a 1300lbs tent trailer. Its a 3000km round trip. In NB there are some seriously steep hills. I have no doubt my BEW can tow this easily, Ive towed a lot more weight then 1300lbs but not for sustained distance like this.

I need an oil change (13,000k on my 5w40 rotella t6) and i was thinking of switching to full synthetic 15w40 to help with cam protection and also to keep oil temps down. I would be sure to change the oil prior to cold weather.

Does anyone see any benefit in doing this, or would 5w40 rotella protect just fine even when pulling weight sustained distances?

p.s I do have an upgraded pd150 oil cooler/ heat exchanger which should help either way.

thanks, james

That is not how oil works. Stick with the correct stuff.

The only thing a 15w40 will do is be three times harder to pump when it is cold (not good).

The "W" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures. For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil.

The second number is the value at 100 C.... both 5w40 and 15w40 are the same at 100 C, both 40. So there would be no advantage to using a 15w40 oil ever. If you for some reason wanted a thicker oil, which there really should be no reason, but if you did, you'd have to switch to a 5w50 or 10w60 or something like that.

I think you'll find the oil temps in your engine will not vary much towing your trailer or not.

oilhammer said:

That is not how oil works. Stick with the correct stuff.

The only thing a 15w40 will do is be three times harder to pump when it is cold (not good).

The "W" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures. For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil.

The second number is the value at 100 C.... both 5w40 and 15w40 are the same at 100 C, both 40. So there would be no advantage to using a 15w40 oil ever. If you for some reason wanted a thicker oil, which there really should be no reason, but if you did, you'd have to switch to a 5w50 or 10w60 or something like that.

I think you'll find the oil temps in your engine will not vary much towing your trailer or not.

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thanks for the quick reply Oilhammer! 5w40 i will stay then.

That's good cause I don't know that they even make a full synthetic 15w-40. I see some blends.

turbotorq said:

In a couple weeks I'm headed out east with the family. We will be towing a 1300lbs tent trailer. Its a 3000km round trip. In NB there are some seriously steep hills. I have no doubt my BEW can tow this easily, Ive towed a lot more weight then 1300lbs but not for sustained distance like this.

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I haven't killed the BRM in my wife's MkV dragging a heavier trailer than that, more miles than you want to go, using stock oil... I've towed it looking like the photo in the link below from Florida to Maine, twice loaded like this...

http://forums.tdiclub.com/showpost.php?p=4966499&postcount=2470

The mesh rear gate on my utility trailer is like towing a parachute. The trip in the photo (first trip), there was at least 1300lbs between the trailer weight, and the stuff on it. That's not counting the full trunk, full back seat, & full roof pod. Not sure if my wife's 85lbs anvil was on that trip, or the second trip in the VW.

The thing to watch when towing is EGTs. Limiting speed or acceleration to keep EGTs in range is worthwhile.

Like mentioned, take it easy, EGTs are the killer, should avoid sustaining above 1600f for more than a few seconds, and 1450f for more than a minute or so. Don't need to be ripping up hills at 140-150 in NB like all of the locals

Other than the turbo the motor will have a pretty easy time.

Yep -- and you need an EGT gauge to do that, which isn't in the stock package, so....

I need an oil change (13,000k on my 5w40 rotella t6) and i was thinking of switching to full synthetic 15w40 to help with cam protection and also to keep oil temps down. I wsure to change the oil prior to cold weather.

thanks, james[/QUOTE]


I thought all rotella t6 was synthetic.

Not a BEW, but the ALH in my Vanagon has faired extremely well on the Rotella T6 5w-40 full synthetic. I've towed extensively with it, including a Popup Camper.

Like others, don't think I've ever seen any full synthetic 15w-40.

As suggested, monitoring the EGTs is probably about as important as anything else when towing. I've seen plus 1000F a few times. However, the gearing in the transmission is such that top gear (4th) is roughly equivalent to 4th gear in the O2J tranny in the NB/Jetta/Golf. The shorter gearing helps keep the EGTs down.

Anyway, below is the rig that we've towed to Alaska twice. It weighs 1200lbs and we generally have at least another 200lbs of junk stuffed inside. Also, the wife packs everything she can in the Van but the kitchen stove (at least another 300 lbs). The second trip up north we took a couple with us as well as all their luggage, stuff, tent, etc.

You can get 15w40 synthetic, royal purple makes it. We use it in 6.0l powerstrokes when the injectors start to get stiction problems.

drucifer said:

I thought all rotella t6 was synthetic.

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All T6 is synthetic but the 15w-40 is called T4 and is NOT synthetic.

https://rotella.shell.com/products/conventional-motor-oil/rotella-triple-protection.html

[note the convention oil right in the URL]

AndyBees said:

As suggested, monitoring the EGTs is probably about as important as anything else when towing.

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I would agree here that this is number 1. But a close second if it's an auto would be transmission temperatures too.

belome said:

All T6 is synthetic but the 15w-40 is called T4 and is NOT synthetic.

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The T4 is the new T3. I'm guessing they switched up the naming convention when they introduced the semi-syn T5. T3, T5, and T6 in the lineup just wouldn't make sense because I'm sure everyone would be wondering what the T4 is. So they just dropped and changed the T3 to T4.

Either way, the T6 is phenomenal oil. It goes in the Dub, Cummins, YZ250F, and the Honda Fury. It meets and exceeds the JASO wet clutch specs for the bikes. Makes oil changes a breeze when you only have to remember 1!

derek5120 said:

You can get 15w40 synthetic, royal purple makes it. We use it in 6.0l powerstrokes when the injectors start to get stiction problems.

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Red Line makes a diesel specific 15W-40, and their 5W-40 rated for gas engines.

Since I accidentally bought a case of the the 15W-40, I will sometimes mix two quarts of the 15W with the 5W for an oil change.

Don't think it will hurt that much living in Kalifornia where the temps rarely drop below 40F.

Lucas oil also has a 15w40 synthetic.

Amsoil makes a 100% synthetic diesel 15w40 engine oil as well. I saw it and was tempted, but if there's no benefit?