# O2 Duration vs Vehicle Service Manager

The clearest difference is review sentiment: Vehicle Service Manager at 75% against O2 Duration's 0%. Vehicle Service Manager also leads on price (Free vs $2.99) and rating (4.7 vs 1.0). O2 Duration's advantage is in-app purchases (none vs 4) and iOS requirement (7.0 vs 17.0). On ads and device support there is nothing between them.

Vehicle Service Manager is free to download; O2 Duration costs $2.99 up front. Vehicle Service Manager sells 4 one-off in-app purchases. O2 Duration asks for nothing beyond the download.

Vehicle Service Manager holds the better App Store score, 4.7 against 1.0. That said, the two scores are not equally well evidenced: Vehicle Service Manager has 32 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 0% of O2 Duration's written reviews are positive against 75% of Vehicle Service Manager's.

O2 Duration ships an update every 15 months, Vehicle Service Manager every 2 weeks. The most recent releases landed on October 15, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | O2 Duration | Vehicle Service Manager |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | [1.0 (1 ratings)](https://appshunter.io/ios/app/o2-duration/id556420187/reviews) | **[4.7 (32 ratings)](https://appshunter.io/ios/app/vehicle-service-manager/id6737859842/reviews)** |
| Number of ratings | 1 | **32** |
| Positive reviews | 0.0% of reviews | **75.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 15 months | **Every 2 weeks** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 1 MB | 21 MB |
| Requires iOS | **7.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Advanced Aviation LLC](https://appshunter.io/developer/540245667) | [Aren Baghramian](https://appshunter.io/developer/1778332077) |

## What reviewers say

### O2 Duration

[App page](https://appshunter.io/ios/app/o2-duration/id556420187)

Calculate the approximate remaining oxygen in portable cylinders. Select your tank size, input current pressure and desired flow rate to see duration in minutes. Features a timer with alerts for low pressure.

**Highlights:** Oxygen cylinder duration calculation, Supports multiple cylinder sizes (A, B, D, E, G, H, K, M), Input current tank pressure, Input desired flow rate, Displays duration in minutes, Running timer with remaining time, Low pressure alerts (500lbs and 0lbs)

**Features:** macOS Compatibility

**In-app purchases:** none


### Vehicle Service Manager

[App page](https://appshunter.io/ios/app/vehicle-service-manager/id6737859842)

Easily track all your vehicle maintenance, service history, and costs. Get reminders for upcoming services and detailed insights into your car's upkeep. Supports multiple vehicles and offers advanced analytics.

**Highlights:** Multi-vehicle garage support, Service reminders, Detailed service logging, Cost tracking and analysis, Mileage/odometer tracking, Export to PDF/CSV

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| A small tip! | $0.99 | one-time |
| Generous Tip | $4.99 | one-time |
| Lifetime | $4.99 | one-time |
| Massive Tip | $14.99 | one-time |


## Frequently asked questions

### Is O2 Duration free?

O2 Duration costs $2.99, with no in-app purchases.

### Is Vehicle Service Manager free?

Vehicle Service Manager is free to download, with in-app purchases available.

### Which has better reviews, O2 Duration or Vehicle Service Manager?

Vehicle Service Manager is rated higher. O2 Duration averages 1.0 out of 5 from 1 ratings, while Vehicle Service Manager averages 4.7 from 32 ratings.

### Do O2 Duration or Vehicle Service Manager have ads?

Neither O2 Duration nor Vehicle Service Manager shows ads.

### Which is updated more often, O2 Duration or Vehicle Service Manager?

O2 Duration ships an update every 15 months, and Vehicle Service Manager every 2 weeks. Most recently, O2 Duration was updated on October 15, 2026 and Vehicle Service Manager on October 24, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*