oil weight to use...synth or dino?

[hurddawg]

I'm a total newbie with the oil and filter scene, this site was recommended to me by a friend. So I'm still learning and I've been searching the forum for the last week.

My car's engine has 195,000 miles (car's mileage is 169,000) and is decent shape. I've changed all the gaskets, the engine has a new head since 189,000 miles and compression is at 170 (dry) with stock compression specs of 162. So I assume the walls and rings (at least compression) are in decent shape. I am thinking (and hoping) that I might have sticky rings, after reading about the Saturn members. So I am also going to try Auto-RX.

Another important factor about the engine is that I've had the car's engine since 175,000 miles and it sat for a full year w/o use. It was "winterized" (used flogger) for that time. When I started the engine after its hibernation, I made sure it was primed, again with Texaco 10w-30 and a primed puralator PureOne filter.

Since I've owned the engine, I've used Texaco oil 10w-30 exclusively, until recently (3mo/3k changes). I switched to Valvoline 10w-40 maxlife, in hope to reduce oil comsumption.

These days it uses about 1qt/1000 miles. And that is with the maxlife. Prior to MAxlife use, the car would burn a lot of oil under acceleration when the engine is cold. That aspect of oil use has gone down considerably. This is most likely because of the 10w-40 weight and recent climate change (got colder).

Since valvoline's reputation isn't as good as I had thought, I've bought a case of Castrol GTX 10w-30. I intend to use this with Auto-RX.

Here are the questions...

1) I've read here 5w-30 or 10w-40 weight isn't fantastic...if the auto-rx doesn't clear up my oil problem, would 20w-50 be a better choice?

2) Is it a bad idea to use 10w-30 with the auto-rx application? Should I stick to 10w-40?

3) Should I change to Synthetic after the auto-rx application? I'm not worried about oil leakage, as all gaskets are fresh as of 189,000 miles. Would there be a benefit? If I change to synthetic I'll use Amsoil, as I can get it locally.

4) Also my car's owners manual only recommends two oil viscosities. 5w-30 from 32F and colder, 10W-30 -10F and warmer. Would 10w-40 or 20w-50 increase wear?

5) Recommended oil change intervals?

Thanks for your time, its a length post.

 

[SteveD2]

Hurddawg, I think that the Castrol GTX 10w-30 will work well with the AutoRX. For your next oil change I think that you would be much better off using a 10w-40 instead of a thinner oil. You could even use a 15w-40 in warm weather. I doubt that you would see increased wear with these higher viscosity oils and you would likely see a major reduction in oil use compared to a thinner oil. I believe that most oil manufacturers use better additives than they did in the past. I don't think that a 10w-40 oil will degrade or fail much sooner than say a 10w-30 oil. I believe that you would be better off to stay away from 20w-50 until your engine burns more oil than it does now. I don't thik that there is any point in putting synthetic oil in such a high mileage vehicle. Good luck.

 

[TooSlick]

Hurddawg,

I would flush out the engine with either AutoRX or the Amsoil engine flush. If you want to try Amsoil, I'd recommend their 15w-40 HD diesel and Marine engine oil, and see how well this controls the oil consumption. AME is a 12 TBN, extended drain formulation and you can go to a 7500 mile/6 month drain interval with it. The viscosity is 15.5 Cst @ 100C, which is about 10% thicker than the Amsoil 10w-40. The Amsoil 15w-40 would actually qualify as a 10w-40 in terms of cold flow properties, but is marketed for HD diesel engines where 15w-40 is still the standard grade ....

TooSlick

 

[hurddawg]

thanks for the replies.

I'm wondering how the Amsoil diesel oil compares with the Mobil Delvac1. Would they be about the same? I was worried about the increased ash content (makes it more of a base, right?), so i didn't mention the diesel oils. Is this something to be worried about? or is the "base-ness" of the oil an anti-acid method?

At this point I think I'll use 15w-40 after the auto-rx doses.