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Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity

Hi Taters, sorry my mistake, I'm using 5W-30 engine oil.

When pulling the trailer, which is about 3500 lbs., it's certainly a struggle for the 4.0. As you know, there is a tranny cooler and the fluid gets up to about 200F on a grade. Not sure if that's too high or not.

If that's high, I'll likely get a larger cooler installed this spring.

I see Ford is discontinuing the Ranger after this year.

Can you rhyme off a few type IV engine oils?

Regards, Paul.
And let's not mention Synlube right now because I'm still in warranty and am not going to consider extended oil change intervals until I'm out of warranty.

He already stated he does not want to do extended drains and asked we not bring that particular subject back up.

Amsoil makes a fine line of products that are group IV and are more readily avialable then most of the other group IV oils at this point. Whether you want to use an oil that is API certified or not again is your choice. The API certified oils Amsoil offers have group III base oils.

I would be looking at your transmission temperatures and personally I would be using a good synthetic gear and transmission fluid.

Thanks for those graphs, Taters, very useful. I think the Amsoil products are the way I'm going to go, especially the tranny fluid.

It's disappointing the way the oil companies advertise their synthetic products. Reading the labels doesn't work. They say, fully synthetic or 100% synthetic. A couple of drops of synthetic oil in their dino oil seems to allow them to fool the general public into thinking that they are buying oil that's actually synthetic, such as Amsoil. Smoke and mirrors...

Can you suggest other Group IV oils that are readily available?
This seems like a good time to post a reply from Royal Purple to Johnny when he asked if they used group III or group IV.

From: "Kyle Neal" <>
Date: July 10, 2008 9:06:12 AM CDT
To: "'Johnny Petree'" <jlpetree@>
Subject: Royal Purple - Base Stock
Reply-To: <>


We're a combination of synthetics including Group III, Group IV's (PAO), and V's (Esters but do not use Polyol Esters)- deciding on which oil is better just by the base stocks is not as simple as some make it out to be. Formulators rarely use a single straight base stock - as solubility, solvency, and seal elastomer compatibility issues can result using a single type of base stock.

The base stock is like flour, flour is flour. The difference is the cake, it is in the way you bake it, mix it, and the ingredients you add to the flour. We do not just focus on the base stock, but the oil as a whole, because it is all in the chemistry.

Have a great day and I hope this helps.

Kyle Neal
Technical Sales Representative
1 Royal Purple Lane
Porter, Texas 77365
work- 281-354-8600 ex 248
cell- 713-705-9556

From: Johnny Petree [mailto:jlpetree@]
Sent: Thursday, July 10, 2008 6:08 AM
Subject: Automotive Question

Can you tell me if your regular automotive oil, not your racing oil, is a Group III or a Group IV synthetic base.

Thank you,

Johnny Petree
Wausau, WI 54403

I have been assuming that you do understand that every synthetic oil has a small percentage of conventional oil that was part of the additive package. The synthetic market is being taken over by lubricants using primarily group III or group V base oils.
Considering all the crap the person has spewed against anyone who dared question or seek reliable information on this synlube.

Considering that said person has stated that it beats him how one who doen't use it can question those who do. (Which by not using it, he does.....Ironic.)

The resistence to using a product that the person spent dozens of posts defending is beyond pathetic.

If said person is so concerned about warranty, which I'll remind him that synlube says they'll cover, then the choice of oil is rather clear.

Whatever meets mfg specs.

An oil such as M1 0w-40 is overkill for a Ranger.
Actually all synthetic oils (>85% synth components) are from 2 types of base oil.
Top synthetic products - usually the most expensive - is a mix of PAO (group IV) and POE/DE (group V).
Budget synthetic products - mix of PAO (group IV) and hydrotreated mineral (Group II or III).
That is due to PAO's low solubility and seal shrinking properties.

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