Thin vs. Thick for sludge removal

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I've noticed that many people advise HDEO for cleaning up a sludgd engine, however if the engine is sludged up why would someone want to use a thick oil? I understand the high detergents of HDEO make it great for cleaning but wouldn't the oil thickness increase the possibility of clogging a passageway? Just a thought...
 
At temperature any oil will be thin enough. I think it's more the impression that a "thin" oil (keeping in mind our propensity to judge stuff at room temp) will sling around and perform scrubbing bubbles action better than one "less thin".

We tend to have vivid imaginations. I'm not saying that I'm exempt from those notions.
 
I'm aware of that, I was saying that the loosened sludge in conjunction with the thicker oil could make it harder for the sludge to move through the system without getting stuck any where. However I think Gary's "sling around" theory is right, I'm imagining a thicker oil remaining more uniform therefore making it harder to move around an obstruction (stuck sludge) therefore a thinner oil would be more ideal since it would have a bigger probability of moving around the obstruction and continuing to move throughout the engine.
 
most people when trying to flush their engines use a thicker oil because they also use a thinner product like MMO or seafoam that lowers the overall viscosity of the oil thus thinning it out.
 
splashing around... a lighter vis oil will splatter off the sludge with less specific impact as the droplet deforms, than a heavier oil.

we could debate this for days...

I've never seen oil do any significant sludge removal, even with seafoam, etc.. screwdriver and a shop-vac, OTOH...

M
 
its not like the splattering oil under a valve cover really has much energy at all anyways. thin vs thick for cleaning the valve cover is negligable. the solvents are what really does the work.
 
I tend to like the thinner ones for cleaning up sludge. My thought is that if the sludge does dissolve into the oil, the oil will most likely thicker as it holds the sludge particles.
 
I too have given this some thought, and i have to narrowly vote THIN.

Reasoning:

If Oil passages are sludged up, let us just say that they are.. a Thin oil SHOULD flow through it BETTER than a Thick one. HDEO T5 Rotella will then make it bigger and bigger, and look for Blackening of the Oil and change Filter and also Oil every 1000 miles if it is working. But Keep on putting Rotella T5 in; MMO if you must. SeaFoam? Maybe before the change. MAYBE.

If you use a Thicker oil, you are basically just thinking it will plunge itself out.

So, id narrowly say, "Thin."

Rotella T5 is 15W-40 anyways, so its right in the middle of thin vs thick.
 
Originally Posted By: HangerHarley
I too have given this some thought, and i have to narrowly vote THIN.

Reasoning:

If Oil passages are sludged up, let us just say that they are.. a Thin oil SHOULD flow through it BETTER than a Thick one. HDEO T5 Rotella will then make it bigger and bigger, and look for Blackening of the Oil and change Filter and also Oil every 1000 miles if it is working. But Keep on putting Rotella T5 in; MMO if you must. SeaFoam? Maybe before the change. MAYBE.

If you use a Thicker oil, you are basically just thinking it will plunge itself out.

So, id narrowly say, "Thin."

Rotella T5 is 15W-40 anyways, so its right in the middle of thin vs thick.


This is exactly what I was thinking, I guess I named the thread wrong. NEW NAME: Which is less likely to cause ill effects during sludge removal- thin or thick?

Both thin or thick oil will both clean properly and really all oils will clean an engine if maintained properly, while Pennzoil may or may not be a better cleaner than others is a discussion for another time. If you are trying to clean an engine don't think that PP and PU are the only cleaning oils out there; QS, Castrol, VV, etc. all have cleaning properties.

I for example am trying to get rid of some sludge at the moment and will be changing the oil this weekend and will be going with QSUD and a quart of MMO. I was going to try PP but the QS is on clearance for $1.30 a quart so I'd be dumb not to buy it...wow this got way off topic...
 
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I think the HDEOs having more dispersant - which they have to have to deal with the soot issue in diesel engines - recommends them for cleaning because it will help keep the dirt, crud (or whatever you want to call it) in suspension doing less harm until it can be drained out with the oil.

And, when I'm really serious about cleaning an engine I have some Marvel Mystery Oil in the crancase with the HDEO (usually Rotella 15 w 40) anyway. That thins it some.
 
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