Oil choses voices in my head

[Tropicalcats]

I am back to thinking about conventional oil vs synthetic oil in my 95 D21 4cyl with 138K
I have read and re read most of the post on this site and others they say never, always and sometimes change to synthetic from conventional. I understand that synthetic may/does breakdown sludge in the engine and this make cause some leaking at the seals but doesn’t a conventional oil break down sludge and help to clean the engine? And so also breaks down the sludge.
I know the real secret is just making sure you change oil on a regular interval.
Just thinking that they both produce the same results of removing sludge that may have collected around seals and with that removed may cause leaks.
So what’s the difference, price? Of course, and I would never go for the allowable time to run a synthetic. I change every 3-4 K miles.
Synthetic or conventional?

[alabama_lowlife]

My 97 rattled like hell when I put synthetic in it once. I changed it after about a week.

[Cusser]

"I have read and re read most of the post on this site and others they say never, always and sometimes change to synthetic from conventional."



That was "the theory" from a decade or more ago. Only "advantage" of synthetic is the extended oil change interval.



I use conventional in my 2 Frontiers (1998 and 2004). Semi-synthetic contains an "unknown mixture" of conventional and synthetic. And most of the molecules are the same between conventional and synthetic anyway.

[cadillacdude1975]

I run the high mileage 5w30.

[89'HBV6]

I run 10-40 dino... usually mobil. Sometime, if I can't get what I need, most any dino does the job in these old trucks.

[cadillacdude1975]

I spent 15 years in the auto service industry. The oils made today are so refined and close in formulation, oil brand really means squat. I grab what ever is in the 15-17 dollar range. Sometimes Valvoline Maxxlife is cheaper from Amazon. Quaker State has been as low as 14 bucks for a 5 quart bag at Wally world. Last time I changed the pathy oil, I used the high mileage Walmart house brand. The one constant is a Wix or Nissan oil filter.

[SBJ]

Adding to what Cadillacdude says, today's oils are good enough it really doesn't matter what brand you use. The important thing is that you change it regularly.

Personally I'm a big fan of synthetic myself and have been running it in pretty much everything for years now. In my experience I've found engines that use synthetic tend to be really clean inside, even after they rack up a lot of miles. FWIW I use mobil 1 high mileage in my daily and either supertech or NAPA synthetic (aka valvoline) for everything else. Costco house brand synthetic is also a really good deal, if you have a membership.

[Deerhurst]

Wix filter (Napa Gold) and Castrol Edge full synthetic. Used it on my VG30 and now in my VG33. My 3.3 does have lifters that sometimes make noise. Been using synthetic for probably close to the last decade. Never had a leak issue.



I only use Castrol edge because I have to have a VW approved oil in my car and edge is the easiest to find in the weight that uses so I just stick to one brand.



I've also extended my oil changes to 7k in the truck. When I pulled my VG30 apart it was spotless inside. No sludge of any sort.