Running in oil - genuine or snake oil?

AliK

Vehicle Dating Officer
Staff member
Club Member
So gang wondering if there are any views on which oil to use for a rebuilt motor's running in period. I've heard from "any oil will do" to "use something designed for it" but which one!?

This one for £27

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Or £30 this one ...

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Or this £30
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Or this at £36

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Or just pour in the tin of Halfords 20w50 I already have knowing it's coming out again in 500 miles and really is it that different to the oils above!?

Help!!!!!!
 

moggy240

Insurance Valuations Officer
Staff member
Club Member
I don't think I have ever really ran an engine in,my metro engine was rebuilt but I think I ran it in with the same oil I was using throughout and changed it after about 500 miles with the same oil.
Not much help I'm afraid.

Sent from my WAS-LX1A using Tapatalk
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I'd use what you have and change it soon.

When I had my engine rebuilt I was told to use Duckams and like you change it early.
 

Huw

Club Member
The company who did the machining on my block supplied me with running in oil. Told to change it after 200 miles and instructions on how to run the engine in.

I’m off there tomorrow to drop s head off, I’ll ask what they recommended.

Huw
 
There's so many schools of thought on running in.

I'm in the, don't labour the engine, happy to rev it as far as it'll go, in the first 20 miles, do 5 or 6 max revs and coast the car under engine breaking for a nice ring seal. Then just enjoy. you never get running-in oil on new cars/bikes do you.
 

Paul_S

Club Member
Nissan's advice on the 370Z is to keep the revs down and not to run the engine at a constant RPM for long periods of time until the running in period is over. I'm trying to remember the numbers (perhaps 3k revs and 1K miles?) There's no mention of an early oil change but I don't know if the oil they supply first time around is any different to the stuff they use when servicing.
 

AliK

Vehicle Dating Officer
Staff member
Club Member
Gents,

Thank you for your brilliant advice all round. As Franky says I have read SOOOO many schools of thought on this one. The common themes in everything I read are:

1. Not running at constant revs but rather driving it as you normally do - so no long motorway journeys and a good excuse for organising lots of summer drive out / meets! :driving:
2. In the first 10-20 miles doing lots of full throttle (not over 4K RPM) followed by engine breaking to get that good push out on the rings and pull back under vacuum
3. Change the oil anywhere between 100-500 miles. I'm with Huw on this one 500 seems too long for my liking.
4. Defo mineral oils - although some US guys I read were chucking in 0W30 fully synth!! :ack:

You've all helped settle my mind - I will use my existing mineral 20W50 to start with, although it does seem awfully "thick" for an engine with better sealing components than my previous engine! Food for thought for another day.

Thanks again all!
 

Jimbo

1978 260z in yellow
Club Member
change the filter only at 200 miles then change the oil and filter at 500.
the filter is whats going to trap any debris that the running in oil is designed to suspend seeing as this will be the worst in the first couple of hundred miles then its worth changing the filter early and then the oil and filter at the correct interval.
as regards not wearing in new engines with break in oil, thats because machining has got a lot better than in the old days so running in oils aren't really required, although there is still a wearing in period the amount of debris and wearing in required is a lot less.
the labs where i work sample oil filters from time to time to see what has been trapped by the filter its still shocking to see what comes out of an engine but it definitely is better than it used to be
 

AliK

Vehicle Dating Officer
Staff member
Club Member
Thanks Jimbo! Great advice again.

This I hadn't heard before.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
When I was a kid (yes we had cars not horses) it was a regular sight to see a car with a sign in the rear window 'Please Pass Running In'.
 

Ian

Club Member
Think its all been said already, use mineral oil, I use cheap oil first startup, run it until warm (never idle) , drive 20 miles and then drop the oil and refill with oil to use for the next 200miles, then change again and at 500 miles and last change at 2000 miles I change to fully synthetic. Limited idling periods, no max rpms but full throttle up to around 400 with engine braking, after 1000 mile I do max rpm full throttle. This is on high compression highly tuned engines though so for a more normal engine less fuss may be required.
 

jonbills

Membership Secretary
Site Administrator
Just to provide a contrary view, I stuck synthetic triple QX 5W40 (+zddp) in my new engine 2 years ago for the first start, ran it at 3000 rpm for 30 mins and just changed the filter. I don’t think I changed the oil until the end of the summer.
 

uk66fastback

Club Member
My rebuilt and stroked to 347 Ford V8 was run for 500 miles with mineral oil and then oil and filter were changed (same kind of oil used again) - car was sold with 2000 on the clock though, so I presume it was okay after.

All this on the instructions of the engine builder.
 
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