can I use synthetic oil

[barishiman]

I've looked through previous posts about synthetic oil and Mobil 1 seems to be the winner. I'm confused though on the fact of rebuilt vs. never rebuilt.

My engine was rebuilt by the previous owner, for all I know there are 30 over pistons. I had my head worked on replacig the seats, 1.75" intake vales, and resurfaced. I have the new oil pump installed and the oil pan sealed.

Is it possible to use Mobil 1 Synthetic with what I have?
I've used Quaker State 10w30 in the past and haven't runned into problems. Just wondering before I put my engine back in.


Andrew

 

[Anonymous]

after 8,000 miles its safe

 

[barishiman]

thats great, now i wish that my odometer would work. Never cable didn't work so I think the gears are bad. I hear creaking from my instrument bezel.


Andrew

 

[ruckus68]

does that mean you shouldn't use mobil 1 (or other synth's) in a newly rebuilt engine?

John

 

[rbohm]

8) you want to wait untill the first regular oil change at 3000 miles. at that point the engine is broken in. you could change at 1000-1500 miles after a rebuild, but i recomend the 3000 change.

 

[Anonymous]

Maybe someone can help explain? Apparently the reasoning is that synthetic oil stops the rings ect from "bedding in" properly on a new engine.
If thats the case then a high quality "non" synthetic mineral based oil that lubricates better than say a lower quality cheaper synthetic oil would likely stop the rings bedding more than the cheaper synthetic oil. Conclusion in this case wouldnt it be better to use the synthetic oil? As in this case it would help to bed the engine in due to less friction?
Im thinking that all this amounts is to get an oil that has a good temperature range that doesnt reduce friction too much so that the engine can "run in" properly. Anyone wish to enlighten me more on this??
I think you can buy oil esspecially for "running in" or alternately get some cheap stuff if my reasoning is correct. Especially if its only staying in for a short time.

Oh, I used to sell an oil additive that we tested in Mobil 1 (the racing Mobil 1 I think) on a special friction wheel. All remmember is that Mobil 1 used to squeal like a pig on the wheel until the additive was added to the oil and then it would go completely silent. I would personally choose something else for the oil in my car.

 

[Anonymous]

Mistake in wording in above the fact that the Synthetic would create more friction not less in this example would mean that the engine would run in better?

 

[CobraSix]

I'm not sure about that whole "don't use synthetic before a certain mileage". I've never heard a mechanic tell me that. Also, most high end cars (especially Euro) come with at least a blend if not pure sythetic.

Generally, I wouldn't do it just because of the frequency of oil changes when you first rebuild an engine. You are supposed to change the oil at 500, 2000, 5000, and every 3000 miles after that.

All that being said, and without any other written evidence...I don't use sythetic until 10k miles. The only written documents I've seen against the use of sythetics in new engines is from my cam installation sheet and says not to use synthetic oil during the break in of the camshaft.

Slade

 

[rbohm]

8) usually it takes the rings and bearing about 500-1000 miles to wear in and fit the cylinder bores and crank properly. after that you can change to synthetic. i usually recomend you change at 3k miles after a rebuild though.

 

[MustangSix]

It depends on the finish that you put on everything.

In years past a standard rebuild would leave lots of machining irregularities. The honing would have a noticeable cross hatch and iron rings might take 500-1000 miles to fully seat.

When I build an engine these days I have Joe use the CK to put a 600 finish on the walls, leaving them looking nearly polished. I also polish the crank. Using moly top rings, the engine is sealed and seated immediately and no break in period is really required other than the obligatory 20 minute run in for a new cam.

Because of this I use synthetic from the start. I change the first filter at 500 miles, but if nothing is amiss, I leave the oil in for the full 7500 mile change interval.

Early synthetics were based on turbine oils and lacked some of the additives and chemistry required to keep some types of automotive seals soft and pliable which led to leaks, but modern synthetics contain every thing needed to be compatible.

If you are going to change your oil every 3000 miles, however, I would recommend you stick with dino oil. If you run a turbo or supercharger, you should run synthetic regardless of change interval.

 

[rbohm]

8) the only flaw i see in your statement jack is the fact that bearings will have high spots on them that need mileage on them to wear down. other than that, if you have no problems you are good to go.

 

[barishiman]

I left the block as is when I pulled it. I have been constantly oiling the pistons and camshaft the best I can and cranking it a few turns. I didn't dis-assemble block except for replacing the oil pump, oil pan seals, and the water pump. The pistons, cam and what not has been broken for six plus years. So I don't have a total rebuild.

Is it okay to go ahead and use Synthetic off the bat or run some regular 10w30 for like a few oil changes then switch over to Synthetic?

thanks for the answers so far, I didn't expect so many after one night.


Andrew

 

[Anonymous]

I have run synthetic in mine since 1990. To this day it does not use any oil (Ok...had a valve cover gasket leak at 75k miles...but changed that out). Knocking an a large pice of wood

My wife's new intrepid came with synthetic in the case from the dealer, and a lot of the other new cars do as well. Now I realixe we are dealing with 30 year old engines here, but on a re-build we are using moden materials (at least for a toal rebuild). Other than it maybe taking a little longer for things to wear in, I really don't see any reason not to run synthetic from the beginning.

Of course, changing at the first oil change would work fine if it puts your mind at ease.

Jim

 

[CobraSix]

Andrew,

So you didn't replace anything like the camshaft, lifters, crank?

If not and all you replaced is the oil pump and water pump, You should be just fine running synthetic in it.

Slade

 

[Anonymous]

Other than the change interval what other advantages are there to Synth oil?

I am curious because I am thinking of using it in the rebuilt engine after an inital break in....

 

[rbohm]

8) synthetic oils on the surface can seen like a paradox. they have high film strength and low pumping losses, it used to be you could have one or the other but not both. they also have long molecule chains that when broken you just have two shorter chain. mineral oils when the molecule chain breaks the chain unravels. in laymans term synthetic oil can help you get better fuel economy, and longer wear from your engine.

 

[barishiman]

I'll be out buying a case of synthetic by the end of the month. I'm almost ready to prime the engine compartment.

Anybody know of an K&N oil filter that fits my 66 200cui?


Andrew

 

[Anonymous]

K&N pn: 3001 for the stock filter type.

 

[Anonymous]

my wife's new Jetta came with synthetic. I was impressed caus ethis was first I ever heard of that coming from factory...usually they want more frequent oil changes to make $$$

 

[Falcon62]

As for new cars coming from the dealer with synth, please remember that we are comparing apples and oranges with regard to our inline six rebuilds. When rebuilding an engine, my personal advice is to talk with your machinist, and follow their recommendation as to when you can make the switch to synth. They know the quality of their machine work and should give you the right answer.

Call me old fashioned, but I still use straight 30w for break-in and up to the first oil & filter change at 500 miles. Then another oil & filter change at 1500, and then again at 3000. At the 1500 mile oil change I refill the crankcase with whatever oil I have decided to use for the life of the engine. Once I hit the 3000 mile mark, I stick to that interval with dino oil or use the synth mfr's recommended change interval.