Engine Oil: what's best?

[an observer]

Oil changed despite mechanics objections, saying it will develop oil leaks on full synthetic.

Not sure what to think about that, but guess ill find out soon enough.

[Rob's 380]

On what basis does he claim that fully synthetic oil causes oil leaks?

[leadfoot6]

There is some discussion, with evidence, at "Bob is the oil guy" about the potential for leaks after switching from "Dino"(dinosaur i.e mineral oil) to synthetic oil-

Recently:

That said, there's no one size fits all rule IMO..if the thought of switching over to a full syn scares you - don't switch. Maybe a nice middle ground for ya is a HiMi syn blend w/extra seal conditioners... there are UOA's in the sub forum of syn blends doing 6k+ mile oci's. Nothing wrong with that in my book...

https://www.bobistheoilguy.com/forum...ic#Post5207177

Some years ago:

My S10 had also been run on dino, mostly VWB, for it's whole life. At about 100k, I made the dumb decision to switch to M1 5w30. Within a few thousand miles, I had leaks from a number of places. Switched back to dino, and the leaks are virtually gone. I know most guys say switching to synthetic will not cause leaks on older vehicles, and I used to be one of those guys- I had done it on several other vehicles, until it happened to me... I'm done switching on vehicles with over 50k on them or more than about 5 years old.

https://www.bobistheoilguy.com/forum...Number=2177122

As pointed out in the first quote:

That said, there's no one size fits all rule IMO..

Not all engines are the same and,

"Oils aint oils, Sol".

I imagine "an observer" has a mechanic who has seen past evidence of such things happening.

[leadfoot6]

In this post dealing with 380/6g75 engines:

https://www.aussiemagna.com/forums/sh...=1#post1641390

Madmagna has suggested Gulf Western Syn X 3000.

It is on special at the seemingly very good price of $19.99 until 29 March at Supercheap:

https://www.supercheapauto.com.au/p/...re/283732.html

The limited number of reviews that I have seen are mostly positive.

My transplanted 6g75 engine in my TL AWD is approaching 6 months from time of installation.

I might give the GW product a try later in the year.

It is semi-synthetic, as opposed to being termed a full-synthetic oil, but I had been using Nulon 10W40 semi-synthetic for a few years in my 6g74 before it was replaced by the 6g75 without any significant problems other than some leaks from the rocker cover gaskets, which was not unexpected @190,000km at time of replacement.

At approximately only 20,000km total travelled from factory new on my new engine(sitting in a warehouse for a lot of years until it was installed by a previous customer of MitsFix), I am not expecting any problems at all.

P.S. The new engine install and all other work carried out by MitsFix is still all 100%.

I picked up two 5l containers whilst still on special.

It will be a few months before I need to change the oil, but I will report when completed.

In a few months my transplanted 380 engine will have been in place for 12 months.

I have purchased the Gulf Western Syn X 3000 semi synthetic that I plan to use.

After reading some of the anecdotal evidence as noted at "BITOG", and other forums, I hesitate to use a full synthetic oil.....

.....just in case.

I am not tempted to do so purely to obtain a marginal decrease in fuel consumption as a result of using a full synthetic oil.

[an observer]

It has been run on semi synthetic for the past five years.

If leaks develop on full synthetic and are intolerable it will be switched back.

Wait and see.

[an observer]

Three weeks in and no leaks found. Hoping this continues. Fluid levels are steady and the garage floor still dry. Nothing underneath and the block and transmission casings all look the same.

[an observer]

Update- two months in and the only change so far is mildly increased usage. Had to top it up this morning for the first time since servicing. But up on the hoist, a good look underneath and all is well so far as far as leaks go.