switch from 5w-30 to 15w-40?

[asn007]

Hello members, I'm currently running Chevron Supreme 5w-30 and thinking about switching to Chevron Delo 15w-40. Both oils are available at Costco and the Delo is actually on sale . The Delo is only available in 15w-40. I have a '92 FJ80 with a 3FE engine with 135k. Is there any downside to switching to the thicker oil? Any loss in protection, MPG, etc? Any upside to switching to the thicker oil? Heard that higher viscosity gives better high temp protection. I live out in CA so the temps never get too cold but will make trips out to Tahoe where it does drop below freezing. Any input/experience is appreciated. TIA

 

[7schulz]

From here:
https://forum.ih8mud.com/80-series-tech/79305-oil-recommendations-discussion-thread-faq.html

Current Favorites are:


Synthetic:

1) Mobil 1 0w-40. This is a great oil, but some have had high consumption with it, others can't find it.

22) Mobil 1 Turbo Diesel Truck 5w-40 (Formerly Mobil 1 Truck & SUV 5w-40). I know that it says Diesel, ignore that part. It is relabeled Mobil Delvac 1, and designed as a fleet oil (gas and diesel engines). Many believe that this is the best oil in the Mobil 1 lineup.

3) Castrol 0w-30 aka German Castrol (THIS OIL APPEARS DISCONTINUED SO LOOK CAREFULLY AT THE BOTTLES BEFORE YOU BUY). You have to be careful with this one as there are two versions, a US made Group III and a German Made Group IV oil. If you want to run this one you have to look carefully at the back of the bottle for those magic words "Product of Germany" or "imported from Germany". The back will also carry BMW LL-01, MB 229.3 and 229.5 approvals.

4) Shell Rotella T 5w-40 Synthetic. This is a group III oil that has turned in consistently good results at bobistheoilguy.com. It is the value leader of the bunch when you can get it at Walmart for $12.88 per gallon. If you have to buy it at $5.00 a quart, buy one of the others above.

5) Mobil 1 Hi Mileage 10w-40. This is a newcomer and availability has been sparse but it should be a great choice and work well when it can be found.

6) Mobil 1 High Mileage 10w-30. MAKE SURE IT IS THIS EXACT MOBIL 1 10W-30 SINCE THEY HAVE 3 DIFFERENT VERSIONS. Yes, I know that I said no Mobil 1 30 weight oils, so why this one? This one, like the German Castrol, is formulated on the heavy end of the 30 weight scale and meets ACEA A3 specs (HTHS of 3.6).


Right now some Mobil 1 is still on shelves that was produced post Katrina outside of their API approved recipe due to not being able to get some of the normal components of this oil, this oil will be marked on the back left "suitable for" and will not have the API Doughnut, the regular stuff is starting to come back on shelves but I cannot get it in my weights locally yet.

I am not sure what exactly is different but if you have a choice get the non "suitable for" bottles.





Mineral (Dino) Oil:

The major brands are all getting pretty good. If you are in a mild climate (temps above 40F), the Chevron Delo 400 15w-40 appears unbeatable, and many times turns in numbers close to the synthetics. For those in colder climates, in the winter, run a 5w-30 if you use mineral and pick your choices from Chevron, Havoline, Pennzoil, or Mobil. The only reason I don't mention castrol GTX is their mineral oils seem to have pretty crummy low temp pump specs. Valvoline is excluded because their All Climate has shown poor performance, but the Maxilife is supposed to be pretty good and is available in 5w-30.

I was always a Valvoline fan, but after reading the oil analysis (actual testing of oil run in cars), I was surprised at how poor Valvoline performed compared to some other dino oils. On average the two best performing dino oils are 1) Chevron Supreme, and 2) Penzoil Purbase. I had heard good things about Chevron oils before, but prior to this had never heard good things about Penzoil. BTW, Chevron is available at Costco.

Many people will start to discuss sludge when Penzoil is mentioned, usually saying something like “my mechanic says Penzoil causes sludge problems.” Penzoil and other Pennsylvania crudes have had problems with sludge. The thing is these problems were 30+ years ago when they were group I oils with 1970’s additive packages. Sludge has not been a problem with these oils for a long time and do not merit any further discussion because the problems were so long ago. Also, note that Penzoil and Quaker State are the same company and their oils are usually identical.

 

[kidglove13]

I am switching to 15w-40 for summer.
If you are going to be in a place where you know that the temps could be consistantly lower than 40 degrees I think that 15w-40 is to heavy.
It all depends on how much time you will be in Tahoe.
If it just a few trips than you should be fine.

 

[Tools R Us]

Delo is good oil. The viscosity depends on operating/starting temp, IIRC in the “for everybody else but USA” Toyota recommended oil chart for the 1FZ, 15W is good to 14F. You may want to check the 3FE chart, but probably good to go with it.

 

[FirstToy]

Costco carries both Delo and Supreme for good prices. Both are ISO-SYN and great quality.
I run Supreme in winter and Delo in summer. No brainer.

 

[LOfi]

I just switched from 5w-30 to Mobil 1 Hi Mileage 10w-40. Found 5 quart containers at Walmart. I had a minor valve cover leak that is no longer leaking and my consumption has stopped. I will probably just run it for the warmer months then switch to something lighter for the winter.

 

[asn007]

Hey thanks everyone! I like the no brainer approach of Delo in the summer, Supreme in the winter. But will going from a lighter oil to a heavier weight oil decrease MPG? Also, will the heavier oil slow down a minor HG leak/ oil consumption? I've got 135k on it & it's a little wet around the spark plugs.

 

[FirstToy]

you need to do a valve cover gasket & spark plug seals.
oil weight is your choice.

 

[asn007]

you need to do a valve cover gasket & spark plug seals.
oil weight is your choice.

I wish I knew how or had the $$$ ...luckily the problem is not critical as she still runs strong. Was hoping the heavier weight oil will seal it up temporarily until I get it fixed.

 

[tirewater]

Using a heavier weight oil can increase fuel consumption. The lower weights are considered energy efficient oils. It appears the cutoff is at 30. Some manufacturers are starting to recommend 5w-20 oil to eak a little bit more mileage...

Personally, I live with the leaks until I can fix them. Is your engine spotless? If it's not, don't worry about a little seepage.

Modern engine tolerances are very tight and sticking with a lower winter rating allows oil to reach critical valve train areas faster on start up. That said, I'm sure our engines don't have the tolerances they used...

 

[asn007]

Using a heavier weight oil can increase fuel consumption. The lower weights are considered energy efficient oils. It appears the cutoff is at 30. Some manufacturers are starting to recommend 5w-20 oil to eak a little bit more mileage...

Personally, I live with the leaks until I can fix them. Is your engine spotless? If it's not, don't worry about a little seepage.

Modern engine tolerances are very tight and sticking with a lower winter rating allows oil to reach critical valve train areas faster on start up. That said, I'm sure our engines don't have the tolerances they used...

Ok, that makes sense. So would it be worth it to go to a 15w-40 for better protection or stick with the 5w-30? I'd like to maintain my environmentally friendly 10 mpg if possible but will switch if it's better engine protection to go heavier.

 

[tirewater]

I can't imagine the mileage savings is that much. Perhaps 2/10 of a MPG extra? That # is purely based on one of those silly calculators on the oil manufacturers website. I suppose even 2/10 of a MPG adds up over the course of a tank.

Personally, I use the cheapest name brand 5w-30 oil (generally valvoline) and change every 3k miles.

Delo is a group II oil, so it uses less wax/parafin additives to achieve its weight. Which of course is good in preventing deposits.

TBH, I don't think it really matters that much this day in age. If you get a good deal on Delo, by all means use it.

 

[Tools R Us]

... But will going from a lighter oil to a heavier weight oil decrease MPG? ...

Yes, but the studies that I have seen show that the change is very small, a fraction of a mpg. Basically undetectable to the average driver, it's main purpose is so the manufacturer can say things like: The fleet of vehicles we made this year will consume a few barrels less fuel over their life than last years fleet.

 

[tirewater]

Hey, that's important when manufacturers must meet CAFE standards. What easier way to reach those standards than by simply changing the oil....

Yes, but the studies that I have seen show that the change is very small, a fraction of a mpg. Basically undetectable to the average driver, it's main purpose is so the manufacturer can say things like: The fleet of vehicles we made this year will consume a few barrels less fuel over their life than last years fleet.

 

[BrotherRob]

I can't imagine the mileage savings is that much. Perhaps 2/10 of a MPG extra? That # is purely based on one of those silly calculators on the oil manufacturers website. I suppose even 2/10 of a MPG adds up over the course of a tank.

Personally, I use the cheapest name brand 5w-30 oil (generally valvoline) and change every 3k miles.

Delo is a group II oil, so it uses less wax/parafin additives to achieve its weight. Which of course is good in preventing deposits.

TBH, I don't think it really matters that much this day in age. If you get a good deal on Delo, by all means use it.

You're driving a 5k brick. The oil isn't slowing you down. I run the thick stuff year around in AZ.

 

[7schulz]

If you don't like the recomendations at my first post go here
Welcome

 

[asn007]

Hey guys, please go check out my new thread on Kragen OReilly's full synthetic oil. I got the spec sheet on it as well. 5 qts & a Mobil 1 filter for $17.99! Take a look and LMK if it's as good as the Delo. TIA!

 

[bwr9300]

oil change

I'm getting ready to do an oil change. I was curious what yall think of rotella t 15w-40?

I've been running 15w-40 since I got the rig 4 months ago and got pretty stoked when I saw this rotella stuff in a gallon jug at wal-mart for under $15.


Shell Rotella t 15w-40 recommended?!

(if so now its time to figure out gallon conversion...errrr)

 

[Ebag333]

Both trucks like 15w-40 better. Less oil usage, and the oil pressure gauge stays more in the middle range.

 

[bwr9300]

I've been running 15w-40.

I'm curious of Shell rotella t 15w-40