V8 Engine Oil - Mineral vs full Synthetic

**BradC** · 5th April 2020, 07:44 PM

Originally Posted by 101RRS

Semi synthetic should be OK but not full synthetic as it seems to go through older engines like a dose of salts.

The general consensus on this is cars that have done a lot of ks on conventional mineral oils tend to harden their seals, and a combination of a hardened seal and carbon residue from minute leakage tends to keep the oil in. Apparently changing to a full synthetic makes a great job of cleaning out the grunge and as a consequence they leak. Newer high-mileage synthetic oils have seal softeners and swellers designed to prevent this.

Newer Viton seals don't seem to be susceptible to this. Most european manufacturers seemed to make that transition in the late 90's.

Seals have improved, but so have synthetic oil blends.

**LRpete** · 6th April 2020, 05:55 AM

Actually I remember reading that 1997 (my year) was the year Landrover changed to Teflon seals on the V8. Would this be the Viton seals you refer to BradC ?

Also I have seen a few people say that changing to full synthetic has resulted in rattly lifters in short order and a need for major engine work.

**Pedro_The_Swift** · 6th April 2020, 06:02 AM

It came to a point my D1 just wouldnt do 5K on its own oil,,
changed to 20w50 and never needed to add extra oil between changes,
Thats 10 years of D1 oil changes/usage ....
thats in QLD mind you,,

Use HPR10 in the BSL and its touch and go to make 10k...

**ian4002000** · 6th April 2020, 06:33 PM

I seem to recall that the reason L34 holden v8's had rocker failures was eventually found to be a lack of oil mist caused by the team changing to synthetic oils. Now this is a long time ago but since knowing this i have never put synthetic into an engine that wasnt designed for it.
Also mineral oils are much improved these days and are very reasonable in price. I would much rather change the oil earlier than use a synthetic.

Ian
Bittern

**Old Farang** · 8th April 2020, 01:25 PM

Originally Posted by ian4002000

I seem to recall that the reason L34 holden v8's had rocker failures was eventually found to be a lack of oil mist caused by the team changing to synthetic oils. Now this is a long time ago but since knowing this i have never put synthetic into an engine that wasnt designed for it.
Also mineral oils are much improved these days and are very reasonable in price. I would much rather change the oil earlier than use a synthetic.

Ian
Bittern

Yes, I was always taught not to use synthetic oils in ANY flat cam engine. But then I am ancient. I run my D1 V8 on 10W 40 Magnatec and it now has over 200K Kms on it, but on LPG for half of that mileage.

**rick130** · 8th April 2020, 04:13 PM

Originally Posted by Old Farang

Yes, I was always taught not to use synthetic oils in ANY flat cam engine. But then I am ancient. I run my D1 V8 on 10W 40 Magnatec and it now has over 200K Kms on it, but on LPG for half of that mileage.

I've been avoiding commenting again but here goes....

Syn oil isn't an issue.

Have run many flat tappet race engines on various syn oils back in the 90's, (there are many different types of synthetics) and Pat Purcell, one of Australia's top race engine builders and race engineers back in the 80's and 90's ran many customer Chevs and Ford's on Mobil 1, BP Visco 5000, etc.
It all came down to how the cam was run in, and during the building process making sure the radius on the lifter was correct and matched the taper on the lobe.
We rejected many lifters as they weren't radiused properly, and the running in procedure was vital to decent cam life.

**ian4002000** · 8th April 2020, 06:44 PM

Originally Posted by rick130

I've been avoiding commenting again but here goes....

Syn oil isn't an issue.

Have run many flat tappet race engines on various syn oils back in the 90's, (there are many different types of synthetics) and Pat Purcell, one of Australia's top race engine builders and race engineers back in the 80's and 90's ran many customer Chevs and Ford's on Mobil 1, BP Visco 5000, etc.
It all came down to how the cam was run in, and during the building process making sure the radius on the lifter was correct and matched the taper on the lobe.
We rejected many lifters as they weren't radiused properly, and the running in procedure was vital to decent cam life.

It wasnt the cams the Holden Team was having problems with. It was lack of mist lubrication to the rocker gear. It took Holden a while to find the problem and at that time they had Mobil 1 for a sponsor so they avoided telling everybody about the cause of the problem. I think they then went over to roller rockers to stop the problem.

Ian
Bittern

Lotusman · 9th April 2020, 07:16 AM

Originally Posted by LRpete

Have 1997 V8 with 155k. Change oil every 5k with Penrite HPR30 20w60 mineral oil.

Have read all the oil threads and thinking of changing to Penrite HPR10 10w50 full synthetic with the zinc levels similar to the HPR30. I don’t think this oil was sold back when I started using HPR30.

What are opinions/views on making this change?

Thanks.

NOT a good idea with that many miles. Oil turns into a solid when in your engine over time and synthetic ( because of it's high detergent characteristics) will wash away all that sludge and your because of the sludge, your clearances will be greater once it leaves. Also you will have a good chance of developing a leak somewhere and it will be much noisier as well.

atb,
Richard
ps guys will tell you that synthetics are not as good for some engines but they have superior characteristics on every level compared to other oils and your engine can't tell the difference what oil is used. All race car owners use it as it gives more hp, runs cooler and parts simply last longer. As do all car manufactures. They also are much cleaner as far as emissions go because of a higher flash point.

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