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Hi folks. I am sure this must have been discussed before somewhere on the forum, but I am struggling a little with the search functionality and couldn't find anything.

I'm after some advice/thoughts on the oil regime for my newly rebuilt 4 cylinder engine. I'd like to fit it this weekend and need to buy some oil, but there is a lot of conflicting info on the web. What I have pared it down to, I think, is this:
1. For start-up and first 500 miles: a non-detergent running-in mineral oil;
2. After 500 miles and careful running-in regime, a good quality 20/50 mineral oil with no detergents.

Any recommendations on specific brands, and the above thoughts?

Thanks
John

johnnyj wrote:Hi folks. I am sure this must have been discussed before somewhere on the forum, but I am struggling a little with the search functionality and couldn't find anything.

I'm after some advice/thoughts on the oil regime for my newly rebuilt 4 cylinder engine. I'd like to fit it this weekend and need to buy some oil, but there is a lot of conflicting info on the web. What I have pared it down to, I think, is this:
1. For start-up and first 500 miles: a non-detergent running-in mineral oil;
2. After 500 miles and careful running-in regime, a good quality 20/50 mineral oil with no detergents.

Any recommendations on specific brands, and the above thoughts?

Thanks
John

Use a good quality running in mineral spec oil from Castrol or Penrith, then after about 500ml change oil and filter and refill with Penrith 20/50 and change every 3000mls. I tend to use VR1 Valvoline in an engine with higher miles on it but in your case stick with Mineral 20/50 for normal road use.
Don't molly coddle your car engine during running in, drive as you would normally but don't labour or over rev it. I have run in many engines around a race track in my racing days never did the engine any harm, although we did rebuild after most races

Pretty much any of the good quality 20/50 oils are fine in our engines.
I am currently running Duckhams Q 20W-50 which was reformulated and relaunched a couple of years ago, before that I was using Castrol Classix XL 20W-50.
Prepared to bet you almost everyone on here will have a different opinion!

dursleyman wrote: ... Prepared to bet you almost everyone on here will have a different opinion!

Yes I used a not to expensive 20W50 oil for running in the Sprint engine in 't Kreng (in 1997).
After initial running in (±600 miles) I changed oil and filter for same spec.
After more running in and rolling road tuning (@ 7000 rpm) oil and filter was again changed, after ±1600 miles.
After that I used good quality 20W50 oil and regular changes (prefer Valvoline VR1 Racing).
That engine is still going strong today and still with good oil pressure.

Hi everyone and many thanks for the info. You have all pretty much confirmed what I had concluded, so today I went to Lubetech in Northampton and bought 5 litres of their Exol Vintage SAE 30 Non Detergent Mineral Classic for running-in, and 5 litres of Exol Classic Mineral 20w50 for post- running in. Fingers crossed!
https://www.lubetechshop.co.uk/

Fingers crossed!

John

Some further questions, while I'm at it (here we go again!!)

Any thoughts on:
4 speed gearbox oil. I intend to re-fill with Comma EP75/80 mineral, GS4 spec. Spec ok?
Brake fluid. Currently the system is completely empty, so I have options. Synthetic or non-synthetic?
Coolant. Best spec?

Hoping to get these in time for the weekend, so any suggestions mightily welcome!

Cheers

John

All brake fluids are 'synthetic'.

DOT 4 or 5.1 are polyethylene-glycol based and can be mixed, the main difference being the boiling point of DOT 5.1 is higher. They are also hygroscopic so absorb water from the atmosphere which is why they need replacement every few years to maintain performance and stop boiling in hard braking conditions. Water absorption also allows some deterioration of the system internals, ie rusting of steel pipes and pistons.

DOT 5 is silicon based and will not mix with the others. However, it is not hygroscopic and therefore does not generally need replacement. DOT 5 also has a high boiling point and, as it does not absorb water, does not tend to allow rusting of internal surfaces.

If the system is completely clean it may be an opportunity to use DOT 5 which will last a lot longer, but it is more expensive (naturally) and must always be used for any topping up or bleeding. Most people manage with DOT 4 for normal street use or DoT 5.1 if there is to be track use.

saabfast wrote: ... DOT 5 is silicon based and will not mix with the others. However, it is not hygroscopic and therefore does not generally need replacement. DOT 5 also has a high boiling point and, as it does not absorb water, does not tend to allow rusting of internal surfaces ...

My local brake supplier advises differently! Due to the fact that it does not absorb water, the moisture in the system will collect at low points. That is because water is heavier than the brake fluid. There it will start corrosion.
Also Silicon fluid is compressible, giving a spongy feel to the pedal. Use a good quality Dot4 instead and change every two years!

johnnyj wrote: ... Coolant. Best spec? ...

I always use of the shelf coolant that doesn't need mixing with water.
Over here it will cost a few Euro's per litre.
And you'll have to drain the coolant on a regular basis because something broke

I use Penrite 10/40 semi synthetic [old engine high zinc] with STP in the 7 & 8, both recently fully rebuilt engines. I use Penrite 5/40 fully synthetic with STP in the Mazda & Toyota shopping trolleys, & Penrite 5/30 fully synthetic with STP in the Honda S2000.

I never "run in" an engine today, as unlike the old days, there is nothing to run in. The days of hand scraped white metal bearings are long past.

I never run an engine without STP in it, & the following is why. It's a long story, so get a coffee if you are interested.

In 1962 I bought a new Morgan +4. After 4,000 miles I decided I was never going to learn to drive it properly on the public road, so did a full racing preparation of the mechanicals, with the plan to do a little hill climbing.

The Morgan distributor invited me to join their team to race at a meeting at Albury, so I started racing. 900 miles of road driving, & 65 miles of practice & racing on the new engine later, we pulled it engine apart to see how it was going. Horror, the big end slippers in the rod cap, [only the cap, not the rod], were down to copper. I was using the very best oil available back then, BP course racing oil.

Just in passing, the BP course came with a little glass jar of zinc liquid to add directly to the engine immediately it was started after an oil change.

We could neither see or measure anything wrong, so rebuilt the thing. Next meeting locally with about 80 miles racing, with the red line reduced from 6500 to 6000, & another strip produced the same result.

We went to Bathurst. 6250 RPM down Conrod, & a check after 40 miles of practice copper, & again after the race on the new slippers.

Rebuilt again, we added Molislip Molybdenum to the oil. We did first one meeting OK then copper again after 2 meetings.

At this time STP entered the Oz market, so we gave it a try. First one meeting then 2 then 3, & finally 4 meetings between checks, & still no copper. I don't know how long the STP could have preserved those bearings, because I sold the car & went racing in a Lotus F2.

After a year or so I bought an old Brabham F2 less engine. A mate & I built an engine using the serious bits from Cosworth & Holbay. It broke the lap record at a major circuit, then I won outright or it's class in combined F1 & F2 races in every race it started for the next 20 months I owned it.

I used to laugh quietly to my self at competitors trundling round closed circuits, "running in" their newly built racing engines. From my experience, with the fuels & oils of the 60s, they needed a decoke & valve grind by the time they decided the engines were run in. I considered my engine "run in" when the oil reached operating temperature. It never failed with that treatment.

We did lap new rings in to our polished bores with Brasso metal polish, & finish lapping the valves the same way, but that was for power, not bedding.

This is just my experience, so not gospel, I give it for what you think it is worth.

Hasbeen