[Zackbo]

I just came from a world of building high-power Subaru engines that normally would take 5w-30, but it was common to use a diesel grade 15w-40 once the engine was past a certain level of horsepower. The heavier oil was proven to protect better under high HP/Load conditions. Of course this was a 2.5L 4 banger making 800+ HP:Wow1:

I know there would be a slight gas mileage hit, but anyone here ever used 5w-30 in the hotter months or when towing a lot?

 

[Ramzaq]

Only oil in a 1500 Hemi should be 5w 20w hot or cold weather.

If you use a heavier oil it could throw some codes and make the engine run strange. The MDS system in the Hemi needs the 5w 20w oil to run properly.

 

[hslager69]

my 2008 hemi has been running on 15w40 for a number of years,but i do keep it plugged in in the cold weather.I've been debating running thinner oil in winter but i have around 20 gal of 15w40 left of a 55gal drum,left over from my farm when i retired.Trying to use it up.runs fine with it.

 

[Hermes1]

I just came from a world of building high-power Subaru engines that normally would take 5w-30, but it was common to use a diesel grade 15w-40 once the engine was past a certain level of horsepower. The heavier oil was proven to protect better under high HP/Load conditions. Of course this was a 2.5L 4 banger making 800+ HP:Wow1:

I know there would be a slight gas mileage hit, but anyone here ever used 5w-30 in the hotter months or when towing a lot?

Your make a valid point, but...

Only oil in a 1500 Hemi should be 5w 20w hot or cold weather.



If you use a heavier oil it could throw some codes and make the engine run strange. The MDS system in the Hemi needs the 5w 20w oil to run properly.

this is correct.

 

[DetroitDoc]

Yup the Hemi is very sensitive to oil weight. Running anything other than 5-20w will mess with your MDS and VVT. There are a lot of hemi's in the 200,000 - 300,000 mile range running the recommended oil. I'd just stick with the recommendation.

 

[VPRPWRD]

As previously stated running a different viscosity oil will set a check engine light. If you have any remaining warranty this can be cause to not cover failed engine components.

 

[GuyGene]

I'm a believer in not going over the top number. I'll use 0w-20, but not 5w-30, etc.

 

[Zackbo]

Ahhhh. Thanks for the advice from all. I had no idea my new Ram was so picky about oil viscosity.

 

[Thunderhorse]

Yep. 5W-20 or nothing

 

[ValleyRacer]

Incredible data

I just came from a world of building high-power Subaru engines that normally would take 5w-30, but it was common to use a diesel grade 15w-40 once the engine was past a certain level of horsepower. The heavier oil was proven to protect better under high HP/Load conditions. Of course this was a 2.5L 4 banger making 800+ HP:Wow1:

I know there would be a slight gas mileage hit, but anyone here ever used 5w-30 in the hotter months or when towing a lot?

On this alleged 800+ hp engine - was it turbo charged? I find that quite amazing. The heavier oil would (potentially) under higher pressures allow for less friction.

 

[RoyJ]

Don't think it's about reducing friction, but maintaining viscosity, and therefore a film layer, under both high heat and high bearing forces (which a high hp forced induction engine develops often).

With my Z06, it's very common for owners to use 5W40 Rotella under track conditions where oil temp can hit 280+.

 

[SLTCRACKER]

Good info I was wondering the same thing because I pull a camper in SWFL in high heat.

 

[primo spaghetti]

if your worried about hot climates or towing, switch to synthetic but dont change the oil weight.

 

[DetroitDoc]

On this alleged 800+ hp engine - was it turbo charged? I find that quite amazing. The heavier oil would (potentially) under higher pressures allow for less friction.

Yes Subaru's WRX STi's are turbocharged and make great horsepower with a turbo upgrade, injectors, fuel pump, intercooler, full exhaust and engine management. They are a little AWD rally cars. 800 is a little uncommon but plenty of daily drivers running around with 600 - 700 HP at the crank (500+ at the wheels).

I had one. At the time I also had a bad ass 1971 Z/28 with a 454. My friend had a Corvette. He always used to say, "I'll race your Camaro, but I don't want anything to do with that WRX".

You haven't lived until you experience an AWD launch in one of these cars. It literally scares people. The look of my corvette owning friends face the first time I launched with his in the passenger seat was priceless.

The best part is it was mild mannered, daily driver, with 4 doors and a trunk that got 26 mpg and was even great to drive in the winter. The only reason I got rid of it is I got I to a lot of trouble with the police. You start getting used to the fact that 1/2 throttle is still 0-60 in 5 seconds and I accumulated so many tickets my license was suspended.

 

[jbac36]

The owners manual for my '02 with 4.7 engine shows 10-30 as the preferred oil form 0 degrees F to 100+, with 5-30 as an option.

I'm using 10-30 synthetic (Mobil 1 High Mileage).

 

[SyN]

Primo gives ya good advice. If you are going to work your 5.7L hard. Look into a Top Name Brand 5W-20 Synthetic.

Though truthfully Any Top Brand 5W-20 dino oil will serve you just as well. I would just change it more often.

Todays Dino oils can easily handle up to 275*F for long periods of times. Most so-called Full Synthetics can cruise at 300*F up to 500*F

If you Tow alot for periods of time? Just change your oil more often.

 

[ValleyRacer]

Quite fascinating on a few accounts

Yes Subaru's WRX STi's are turbocharged and make great horsepower with a turbo upgrade, injectors, fuel pump, intercooler, full exhaust and engine management. They are a little AWD rally cars. 800 is a little uncommon but plenty of daily drivers running around with 600 - 700 HP at the crank (500+ at the wheels).

I had one. At the time I also had a bad ass 1971 Z/28 with a 454. My friend had a Corvette. He always used to say, "I'll race your Camaro, but I don't want anything to do with that WRX".

You haven't lived until you experience an AWD launch in one of these cars. It literally scares people. The look of my corvette owning friends face the first time I launched with his in the passenger seat was priceless.

The best part is it was mild mannered, daily driver, with 4 doors and a trunk that got 26 mpg and was even great to drive in the winter. The only reason I got rid of it is I got I to a lot of trouble with the police. You start getting used to the fact that 1/2 throttle is still 0-60 in 5 seconds and I accumulated so many tickets my license was suspended.

I find in interesting (but incredulous) that a stock WRX can handle 800 hp with a loss of 200+ hp at the wheels.
How did that 1971 Z28 handle? :Hey:

 

[dirt dauber]

I've been running 10w-40 conventional oil in my ram 1500 4x4 since new in 1999
146,000 miles later,still no problems and I live in florida
as long as you change your oil regularly,it doesn't matter what oil you run
I use regular oil and change every 3,000 miles
synthetic oil to me is wasted money

 

[Rambunkshuss]

Follow the owners manual recommendations...period
Hemi`s with MDS = 5W20 synthetic oils are the best choice.

 

[Zackbo]

I find in interesting (but incredulous) that a stock WRX can handle 800 hp with a loss of 200+ hp at the wheels.
How did that 1971 Z28 handle? :Hey:

The loss is due to the parasitic effect of the AWD drivetrain.

A stock WRX can't handle this. The tranny assplodes at around 400 ft/lb give or take depending on how you launch. The STI has basically a bulletproof tranny.

My 04 STI had around 700 crank HP. Dynoed around 550. This was my daily driver. Makes for an interesting ride at 3000 lbs. curb weight. Still got over 20 mpg. I could push the boost and timing up a little more and get to over 600 on the dyno when running race gas and injecting methanol. This is why I quoted 800 hp as the OP. Loved the car, but there's a point where it gets unstreetable b/c it's just dangerous to get on it unless your at the drag strip or a closed circuit track. Plus every flippin' teenager with a Honda Civic wants to race you to work every day:i_rolleyes: So I sold it last fall and got a 2014 Tacoma. Then got a 27 ft. travel trailer. Decided it was too much for the Tacoma so that's how I'ze got my Ram:smileup: