Dino oil needed for proper break in, Myth?

[2000NWXJ]

I understand that this could be tossed out as myth for new vehicles, but what about older rebuilt engines such as my 4.0 straight six? The guys that rebuilt my engine told me conventional oil was essential for proper break-in and should be run for the first 5000 miles. What I learned in Motor oil 101 is that 90% of engine wear occurs at start-up and that I should be using as thin an oil(cold) as possible such as a synthetic. I would assume these engines were designed and tested using conventional oil, is the engine wear actually part of a necessary break-in process, or am I missing something here. I know that my engine will run on virtually any form of lubrication but it is prone to overheating, so any way I can improve flow and reduce friction would be beneficial. As of now I'm leaning towards a thinner conventional to be safe such as a 5w30.

 

[Donald]

Marshall engines told me the same thing for my Jeep 4.0. I saw no big deal in running it on dino for 5K miles.

But remember this is a reman or rebuilt engine. A new engine from a major car company is made using very sophisticated machinery and some with coatings.

Several cars come off the line with synthetic oil (Corvette).

 

[Clevy]

The jeep 4.0 doesn't like thin oil. Its a low rev tractor engine. Great torque. Talk to KCJeep. His experience with that engine is second to very few,and he's got uoa data to back up his opinion.
New engines today are coming with high moly synthetic break in oils,from the factory. I was always taught no moly and conventional for engine break in however these oem's are known for durable,long lived engines,so is there any truth to the myth. Maybe at some point there was some truth to it however in practice to me its obvious that moly and synthetics don't negatively affect break in,or oem's certainly wouldn't ship the engines with that type oil in the sump.

 

[2000NWXJ]

Thanks guys, I talked to you yesterday Clevy and I did contact KCjeep and he said I did not need to run Full Synthetic but I guess I would see if it could be beneficial in any way. He said the best used oil analysis for this motor came from Rotella, Valvoline, and QS Defy. I had planned on using conventional rotella 10w30 for the first 5000 then going to the T5, should I use a 5w30 or a 0w30 to help reduce warm up periods?

 

[Stelth]

I took an engine rebuilding class a little over 25 years ago, and the instructor preferred straight sae 20 non-detergent for the initial run-in (20 min at 2000 rpm) and the first 100 miles. His reasoning was that he didn't want anything abrasive suspending in the oil.

I don't know if he was right or wrong, just passing on what he said.

There has been a persistent idea that the rings will not seat properly with synthetic, although, again, I have no idea if there's any truth to it. It's obviously not true of Corvettes, or Mercedes that have synthetic from the factory, but those are new engines.

 

[GutsyGecko]

When we fired up my viper for the first time, we used mobil 0w-40, let it warm up for a few minutes varying the rpm, then we pulled it into the street, did a huge burnout, and took it out to see what it would do.

 

[Errtt]

Do the shops still have break-in oils OTC?
Been a long while, seems the last one I seen was Elderbrock 30 Break-In oil.

 

[Ayrton]

It really depends on the engine, not necessarily "dino," oil, but some engines shouldn't have certain additives during break in.

Example, I know that M272 & M273 Mercedes engines had a Shell break in oil because they did *NOT* want Moly in them during the first 10,000 miles. The moly could have prevented certain special coated components (I'm not a big engine guy to know the correct terms) from sitting in correctly. If Moly got in the engine too soon, the engines could consume more oil later one.

Therefore, I'd follow the recommendation of the shop.

I will say though it's hard in today's time to find an oil off the shelf because they all have so many different additives and many are blends even if not full synthetic. Plus, many conventional still have moly which as in the case of Mercedes, what they did not want during break in.

However, other cars come from the factory with oil loaded with moly (even hand built AMG Mercedes), so it truly varies engine to engine what is needed.

 

[y_p_w]

The issue should be if there really is that kind of mineral oil these days. All the modern oils have additive packs that are nothing like those from old motor oils. Even 30 wt could have a high inherent VI using a group II base oil along with a modern additive package with friction modifiers.

I have seen some obscure house or generic brands with oddball stuff like API SF 10w30 or 30 wt. It is possible to find mineral based non-detergent motor oils. But putting in Pennzoil conventional isn't anywhere near what anyone would think if as a "Conventional oil" that would have been recommended for break in during the 70s.

So how old is this engine? I understand it was common for AMC/Jeep from the 60s for more than 40 years.

 

[2000NWXJ]

I actually don't know how old the engine is itself. I have a 2000 Cherokee XJ, bought a prebuilt block, and gave them my block. I would assume it would have been from a 97+ Cherokee but Jeep put that engine in a lot of rigs.

 

[Clevy]

Originally Posted By: 2000NWXJ
I actually don't know how old the engine is itself. I have a 2000 Cherokee XJ, bought a prebuilt block, and gave them my block. I would assume it would have been from a 97+ Cherokee but Jeep put that engine in a lot of rigs.


Oh. So its a reman engine. Ring seat is all that's really required with those. Bearings may be new,most everything else is re-used stuff. Not that that is bad or wrong.

 

[2000NWXJ]

The new parts include:

Pistons, Wrist pin bushings, camshaft bearings, rod bearings, auxilary bearings, timing components, gaskets/seals, rocker arms or cam followers, piston rings, wrist pins, valve lifters, main bearings, oil pump or kit, freeze plugs, and valve guides.

 

[Thax]

I personally would just break it in using Rotella 10w30 or QS Defy 10w30. No need for any fancy oil in a 4.0L and the flat tappet camshaft will benefit from slightly higher zddp content during break in. After it is properly broken in , there is no need for increased zddp due to low valve pressures although it wont hurt it. Like Clevy stated it is a tractor engine really lol. I run QS Defy 10w30 in mine and am very happy with it . The oil is cheap to run and performs very well in this engine.

 

[OneEyeJack]

Red Line has a break-in additive used to protect the camshaft and followers and not interfere with seating the rings. If your engine builder uses a good honing machine there's little worry about the rings seating. Don't it manually depends much more on the operator and you might be taking a chance on the outcome. If your engine had been properly fitted and put together the rings will seat in about the time it takes to drive around the block.

 

[Realtech214]

Wouldnt this " myth " mean that conventional oil will cause more engine wear that synthetic? Thats hardly true???

 

[3putter]

Rotella 10w30 would be my choice, both now and in the future.

 

[default]

Good enough to run in corvettes and vipers, good enough for me. I'd be breaking in on dyno because its cheap and will be drained soon, no other reason.